FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
NON-INVASIVE SUBSTANCE ANALYZER
MITSUBISHI ELECTRIC CORPORATION A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
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DESCRIPTION
TECHNICAL FIELD
[0001] The present disclosure relates to a non-invasive substance analyzer.
5 BACKGROUND ART
[0002] Japanese Patent Laying-Open No. 2017-519214 (PTL 1) discloses a non-invasive
analysis system that includes an optical medium, an infrared light source, a probe light
source, and a photodiode. Specifically, a biological sample is mounted on the optical
medium. The infrared light source emits infrared light. The infrared light passes
10 through the optical medium, and is irradiated on the biological sample. The infrared
light is absorbed by the biological sample, and thereby the biological sample generates
heat. The amount of absorption heat in a biological sample depends on the amount or
concentration of biological components in the sample or on the surface of the sample.
[0003] The probe light source emits probe light, which is visible light, toward the optical
15 medium. The probe light is totally internally reflected at an interface between the
optical medium and the biological sample and exits from the optical medium. The heat
absorbed by the biological sample is transferred to the optical medium, which changes
the refractive index of the optical medium. The change in the refractive index of the
optical medium affects the total internal reflection of the probe light at the interface
20 between the optical medium and the biological sample, which changes the travelling
direction of the probe light exiting from the optical medium. The photodiode functions
as an optical position sensor to detect a change in the travelling direction of the probe
light. The amount or concentration of a biological component is measured from the
change in the travelling direction of the probe light detected by the photodiode. For
25 example, if the sample is a patient's skin, the patient's blood glucose level is measured as
a biological component.
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CITATION LIST
PATENT LITERATURE
[0004] PTL 1: Japanese Patent Laying-Open No. 2017-519214
SUMMARY OF INVENTION
5 TECHNICAL PROBLEM
[0005] However, in the non-invasive analysis system disclosed in PTL 1, the photodiode
has a large size so as to cope with the change in the travelling direction of the probe light.
Therefore, it is difficult to miniaturize the non-invasive analysis system. The present
disclosure has been made in view of the above-mentioned problem, and an object of the
10 present disclosure is to provide a non-invasive substance analyzer that can be
miniaturized.
SOLUTION TO PROBLEM
[0006] The non-invasive substance analyzer of the present disclosure includes an optical
waveguide circuit, an excitation light source, a probe light source, and a first light
15 intensity detector. The optical waveguide circuit has a first main surface including a
sample mounting region and a second main surface opposite to the first main surface.
The excitation light source emits excitation light toward a sample mounted on the sample
mounting region. The probe light source emits probe light. The optical waveguide
circuit includes a first optical waveguide to which the probe light is incident, a
20 waveguide-type ring resonator which is optically coupled to the first optical waveguide,
and a second optical waveguide which is optically coupled to the waveguide-type ring
resonator. The first light intensity detector is optically coupled to the second optical
waveguide and detects an intensity of first light which is a part of the probe light and is
optically coupled to the second optical waveguide.
25 ADVANTAGEOUS EFFECTS OF INVENTION
[0007] In the non-invasive substance analyzer of the present disclosure, the first light
intensity detector detects a change in the intensity of the probe light coupled to the second
optical waveguide due to the ON/OFF of the excitation light instead of a change in the
position of the probe light due to the ON/OFF of the excitation light. Therefore, the
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first light intensity detector is miniaturized, and thereby the non-invasive substance
analyzer is miniaturized.
BRIEF DESCRIPTION OF DRAWINGS
[0008] Fig. 1 is a schematic plan view of a non-invasive substance analyzer according to
5 a first embodiment;
Fig. 2 is a schematic cross-sectional view of the non-invasive substance analyzer
according to the first embodiment taken along a cross-sectional line II-II illustrated in
Fig. 1;
Fig. 3 is a schematic cross-sectional view of the non-invasive substance analyzer
10 according to the first embodiment taken along a cross-sectional line III-III illustrated in
Fig. 1;
Fig. 4 is a graph illustrating a relationship between a phase of a waveguide-type
ring resonator and a coupling rate of probe light from a first optical waveguide to the
waveguide-type ring resonator;
15 Fig. 5 is a flowchart of a non-invasive substance analysis method according to
the first embodiment;
Fig. 6 is a schematic plan view of a non-invasive substance analyzer according to
a second embodiment;
Fig. 7 is a flowchart of a non-invasive substance analysis method according to
20 the second embodiment;
Fig. 8 is a schematic plan view of a non-invasive substance analyzer according to
a third embodiment;
Fig. 9 is a schematic cross-sectional view of the non-invasive substance analyzer
according to the third embodiment taken along a cross-sectional line IX-IX illustrated in
25 Fig. 8;
Fig. 10 is a graph illustrating a relationship between a phase of a waveguide-type
ring resonator and a coupling rate of probe light from a first optical waveguide to the
waveguide-type ring resonator;
Fig. 11 is a flowchart of a non-invasive substance analysis method according to
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the third embodiment;
Fig. 12 is a schematic plan view of a non-invasive substance analyzer according
to a fourth embodiment;
Fig. 13 is a schematic plan view of a non-invasive substance analyzer according
5 to a fifth embodiment;
Fig. 14 is a schematic cross-sectional view of the non-invasive substance analyzer
according to the fifth embodiment taken along a cross-sectional line XIV-XIV illustrated
in Fig. 13;
Fig. 15 is a schematic plan view of a non-invasive substance analyzer according
10 to a sixth embodiment;
Fig. 16 is a schematic cross-sectional view of the non-invasive substance analyzer
according to the sixth embodiment taken along a cross-sectional line XVI-XVI illustrated
in Fig. 15;
Fig. 17 is a schematic plan view of a non-invasive substance analyzer according
15 to a seventh embodiment;
Fig. 18 is a schematic cross-sectional view of the non-invasive substance analyzer
according to the seventh embodiment taken along a cross-sectional line XVIII-XVIII
illustrated in Fig. 17;
Fig. 19 is a schematic cross-sectional view of a non-invasive substance analyzer
20 according to a modification of the seventh embodiment;
Fig. 20 is a schematic plan view of a non-invasive substance analyzer according
to an eighth embodiment; and
Fig. 21 is a schematic cross-sectional view of the non-invasive substance analyzer
of the eighth embodiment taken along a cross-sectional line XXI-XXI illustrated in Fig.
25 20.
DESCRIPTION OF EMBODIMENTS
[0009] Hereinafter, embodiments will be described. The same components will be
denoted by the same reference numerals, and the description thereof will not be repeated.
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[0010] First Embodiment
A non-invasive substance analyzer 1 according to a first embodiment will be
described with reference to Figs. 1 to 4. With reference to Figs. 1 to 3, the non-invasive
substance analyzer 1 mainly includes an optical waveguide circuit 10, an excitation light
5 source 23, a probe light source 26, a light intensity detector 30, and a substance analysis
unit 33.
[0011] With reference to Fig. 1, the probe light source 26 emits probe light 27. The
probe light source 26 is, for example, a laser light source such as a laser diode. In the
present embodiment, the probe light source 26 is disposed outside the optical waveguide
10 circuit 10. The probe light source 26 may be disposed on a substrate 15.
[0012] The wavelength of the probe light 27 is, for example, 1100 nm or more. The
wavelength of the probe light 27 may be 1300 nm or more. The wavelength of the
probe light 27 is, for example, 1700 nm or less. Thus, an inexpensive laser diode for
optical communication such as an InGaAsP laser diode or an InGaNAs laser diode may
15 be used as the probe light source 26. Further, since the probe light 27 is not visible light,
the risk for the probe light 27 to damage the human eye may be reduced. The output of
the probe light 27 is, for example, 5 mW or less. Therefore, the risk for the probe light
27 to damage the human eye may be reduced.
[0013] With reference to Figs. 1 to 3, the optical waveguide circuit 10 has a main surface
20 10a and a main surface 10b opposite to the main surface 10a. The optical waveguide
circuit 10 includes a substrate 15, a first optical waveguide 11, a waveguide-type ring
resonator 12, a second optical waveguide 13, and a cladding layer 14. The optical
waveguide circuit 10 may further include termination portions 16 and 17.
[0014] The substrate 15 supports the first optical waveguide 11, the waveguide-type ring
25 resonator 12, the second optical waveguide 13, and the cladding layer 14. The substrate
15 has a main surface 10b. The substrate 15 is, for example, a silicon substrate.
[0015] The probe light 27 is incident on the first optical waveguide 11 of the optical
waveguide circuit 10. The first optical waveguide 11 includes an end 11a to which the
probe light 27 is incident and an end 11b opposite to the end 11a. The first optical
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waveguide 11 has a higher refractive index than the cladding layer 14. The probe light
27 propagates in the first optical waveguide 11. The first optical waveguide 11 is, for
example, a silicon waveguide.
[0016] The waveguide-type ring resonator 12 is optically coupled to the first optical
5 waveguide 11. The waveguide-type ring resonator 12 has a higher refractive index than
the cladding layer 14. The probe light 27 propagates in the waveguide-type ring
resonator 12. The waveguide-type ring resonator 12 has a thermo-optical effect. The
waveguide-type ring resonator 12 is, for example, a silicon waveguide. The thermooptical coefficient of silicon is 2.3 × 10-4
(K-1
). Silicon has a relatively large thermo10 optical coefficient among optical materials for optical waveguides.
[0017] The second optical waveguide 13 is optically coupled to the waveguide-type ring
resonator 12. The second optical waveguide 13 has a higher refractive index than the
cladding layer 14. The probe light 27 propagates in the second optical waveguide 13.
In a plan view of the main surface 10a, the second optical waveguide 13 is disposed
15 symmetrically to the first optical waveguide 11 with respect to the waveguide-type ring
resonator 12. The second optical waveguide 13 includes an end 13a optically coupled
to the light intensity detector 30 and an end 13b opposite to the end 13a. The ends 11a
and 13a are on the same side of the waveguide-type ring resonator 12. The ends 11b
and 13b are on the same side of the waveguide-type ring resonator 12.
20 [0018] The cladding layer 14 separates the first optical waveguide 11, the waveguidetype ring resonator 12, and the second optical waveguide 13 from the substrate 15. The
cladding layer 14 covers the first optical waveguide 11, the waveguide-type ring
resonator 12, and the second optical waveguide 13. The cladding layer 14 has a main
surface 10a. The thermal conductivity of the cladding layer 14 is smaller than the
25 thermal conductivity of the substrate 15. The cladding layer 14 is made of, for example,
silica glass.
[0019] The probe light 27 incident on the first optical waveguide 11 from the probe light
source 26 is mainly divided into first light 27a which is optically coupled to the second
optical waveguide 13 via the waveguide-type ring resonator 12 and second light 27b
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which propagates in the first optical waveguide 11 without being coupled to the
waveguide-type ring resonator 12. Fig. 4 illustrates a coupling rate of the probe light
27 from the first optical waveguide 11 to the waveguide-type ring resonator 12. The
coupling rate of the probe light 27 from the waveguide-type ring resonator 12 to the
5 second optical waveguide 13 is the same as the coupling rate of the probe light 27 from
the first optical waveguide 11 to the waveguide-type ring resonator 12. The horizontal
axis in Fig. 4 represents a phase of the waveguide-type ring resonator 12 with respect to
the wavelength of the probe light 27, which is defined by the following equation (1).
[0020] Phase of the waveguide-type ring resonator 12 = 2π × (nL)/λ (1)
10 Where n represents a refractive index of the waveguide-type ring resonator 12, L
represents a length of the waveguide-type ring resonator 12, NL represents an optical
path length of the waveguide-type ring resonator 12, and λ represents the wavelength of
the probe light 27. In Fig. 4, m is a natural number.
[0021] When the phase of the waveguide-type ring resonator 12 is an even multiple of π,
15 the coupling rate of the probe light 27 from the first optical waveguide 11 to the
waveguide-type ring resonator 12 is maximum. As the phase of the waveguide-type
ring resonator 12 gets closer to an even number multiple of π from an odd number
multiple of π, the coupling rate of the probe light 27 from the first optical waveguide 11
to the waveguide-type ring resonator 12 changes more rapidly.
20 [0022] The free spectral region Δf of the waveguide-type ring resonator 12 (i.e., the
interval of a frequency at which the coupling rate of the probe light 27 from the first
optical waveguide 11 to the waveguide-type ring resonator 12 is maximum) is given by
equation (2).
[0023] Δf = c/(nL) = (fλ)/(nL) (2)
25 Where c represents light speed in vacuum.
[0024] With reference to the equations (1) and (2), when the refractive index n of the
waveguide-type ring resonator 12 or the wavelength λ of the probe light 27 changes, the
phase and the free spectrum region Δf of the waveguide-type ring resonator 12 change,
which causes the coupling rate of the probe light 27 from the first optical waveguide 11
- 9 -
to the waveguide-type ring resonator 12 to change.
[0025] With reference to Fig. 1, the termination portion 16 is provided at the end 11b of
the first optical waveguide 11. The termination portion 17 is provided at the end 13b
of the second optical waveguide 13. The termination portion 16 or 17 is a light scatterer
5 that scatters the probe light 27 or a light absorber that absorbs the probe light 27. The
termination portion 16 or 17 scatters or absorbs the probe light 27 to reduce the return
light of the probe light 27 that travels to the waveguide-type ring resonator 12, the probe
light source 26, and the light intensity detector 30. The termination portion 16 or 17 is
formed from, for example, a tapered waveguide that easily scatters light to the outside of
10 the waveguide and an electrode (for example, a metal electrode) that absorbs scattered
light.
[0026] With reference to Figs. 1 to 3, the main surface 10a of the optical waveguide
circuit 10 includes a sample mounting region 19 on which a sample 21 is mounted. The
sample 21 is, for example, a patient's skin or body fluid. In a plan view of the main
15 surface 10a, the sample mounting region 19 is located inside the waveguide-type ring
resonator 12, and is surrounded by the waveguide-type ring resonator 12.
[0027] With reference to Figs. 2 and 3, the excitation light source 23 emits excitation
light 24 toward the sample 21 mounted on the sample mounting region 19. The
wavelength of the excitation light 24 is determined according to the absorption
20 wavelength of a substance in the sample 21 or on the surface of the sample 21. The
wavelength of the excitation light 24 may be longer than the wavelength of the probe
light 27. The excitation light 24 is, for example, mid-infrared light. The wavelength
of the excitation light 24 is, for example, 6.0 μm or more. The wavelength of the
excitation light 24 may be 8.0 μm or more. The wavelength of the excitation light 24
25 is, for example, 13.0 μm or less. The wavelength of the excitation light 24 may be 11.0
μm or less. The excitation light 24 may have a plurality of wavelengths. For example,
when the noninvasive substance analyzer 1 is used to measure the blood glucose level of
a patient, the wavelength range of the excitation light 24 is such a wavelength range that
includes the wavelength of the fingerprint spectrum of blood sugar (for example, a
- 10 -
wavelength range of 8.5 μm or more and 10 μm or less). The excitation light source 23
is, for example, a quantum cascade laser that can emit broadband mid-infrared light.
The sample 21 may be irradiated with the excitation light 24 together with reference light
that is not absorbed by the substance in the sample 21 or on the surface of the sample 21.
5 [0028] The excitation light 24 is absorbed by the substance in the sample 21 or on the
surface of the sample 21. The absorption of the excitation light 24 by the substance
generates absorption heat in the sample 21. The absorption heat in the sample 21 is
conducted to the waveguide-type ring resonator 12, which causes the temperature of the
waveguide-type ring resonator 12 to change. The waveguide-type ring resonator 12 has
10 a thermo-optical effect. Therefore, when the temperature of the waveguide-type ring
resonator 12 changes, the refractive index of the waveguide-type ring resonator 12
changes, which causes the coupling rate of the probe light 27 from the first optical
waveguide 11 to the second optical waveguide 13 via the waveguide-type ring resonator
12 to change.
15 [0029] The substance in the sample 21 or on the surface of the sample 21 is, for example,
a biological component. Specifically, when the non-invasive substance analyzer 1 is
used to measure the blood glucose level of a patient, the substance to be analyzed by the
non-invasive substance analyzer 1 is blood sugar contained in interstitial fluid in the
epidermal tissue of the patient.
20 [0030] In the present embodiment, the excitation light source 23 is disposed to face the
main surface 10a. The excitation light 24 is incident on the sample 21 from the side of
the main surface 10a. The excitation light 24 is incident on the sample 21 without
passing through the substrate 15. If the substrate 15 is transparent to the excitation light
24, the excitation light source 23 may be disposed opposite to the main surface 10b of
25 the optical waveguide circuit 10, and the excitation light 24 may be incident on the
sample 21 through the substrate 15.
[0031] With reference to Fig. 1, the light intensity detector 30 is optically coupled to the
end 13a of the second optical waveguide 13. The light intensity detector 30 detects the
intensity of the first light 27a which is a part of the probe light 27 and is optically coupled
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to the second optical waveguide 13. The light intensity detector 30 measures a first
intensity of the first light 27a incident on the light intensity detector 30 when the sample
21 is not irradiated with the excitation light 24 and a second intensity of the first light
27a incident on the light intensity detector 30 when the sample 21 is irradiated with the
5 excitation light 24. As described above, between a time when the sample 21 is not
irradiated with the excitation light 24 and a time when the sample 21 is irradiated with
the excitation light 24, the temperature of the waveguide-type ring resonator 12 changes,
which causes the coupling rate of the probe light 27 from the first optical waveguide 11
to the second optical waveguide 13 via the waveguide-type ring resonator 12 to change.
10 Therefore, the second intensity of the first light 27a is different from the first intensity of
the first light 27a.
[0032] The light intensity detector 30 outputs the first intensity of the first light 27a and
the second intensity of the first light 27a to the substance analysis unit 33. The light
intensity detector 30 is, for example, a photodiode such as a SiGe photodiode. In the
15 present embodiment, the light intensity detector 30 is disposed on the substrate 15. The
light intensity detector 30 may be disposed outside the optical waveguide circuit 10.
[0033] The non-invasive substance analyzer 1 analyzes the substance based on the
intensity of the first light 27a which is a part of the probe light 27 and is optically coupled
to the second optical waveguide 13. With reference to Fig. 1, the substance analysis
20 unit 33 is connected to the light intensity detector 30. The substance analysis unit 33
receives the first intensity of the first light 27a and the second intensity of the first light
27a from the light intensity detector 30. The substance analysis unit 33 determines the
type, amount, or concentration of the substance in the sample 21 or on the surface of the
sample 21 from the first intensity of the first light 27a and the second intensity of the first
25 light 27a.
[0034] The substance analysis unit 33 is, for example, a microcomputer that includes a
processor, a random access memory (RAM), and a storage device such as a read only
memory (ROM). As the processor, for example, a CPU (Central Processing Unit) may
be employed. The RAM functions as a working memory that temporarily stores data
- 12 -
to be processed by the processor. The storage device stores, for example, a program to
be executed by the processor. In the present embodiment, when the processor executes
the program stored in the storage device, the substance analysis unit 33 determines the
type of the substance in the sample 21 or on the surface of the sample 21 or calculates
5 the amount or concentration of the substance in the sample 21 or on the surface of the
sample 21 from the first intensity of the first light 27a and the second intensity of the first
light 27a. The various processes in the substance analysis unit 33 are not limited to
being executed by software, and may be executed by dedicated hardware (electronic
circuit).
10 [0035] A non-invasive substance analysis method of the present embodiment using the
non-invasive substance analyzer 1 will be described with reference mainly to Fig. 5.
[0036] The non-invasive substance analysis method of the present embodiment includes
mounting the sample 21 on the sample mounting region 19 (S1). When there is a
difference between the temperature of the optical waveguide circuit 10 and the
15 temperature of the sample 21, heat transfer occurs between the optical waveguide circuit
10 and the sample 21. This heat transfer makes it difficult to detect a change in the
coupling rate of the probe light 27 from the first optical waveguide 11 to the second
optical waveguide 13 via the waveguide-type ring resonator 12 due to the absorption heat
in the sample 21, which makes it difficult to analyze the substance in the sample 21 or
20 on the surface of the sample 21. Therefore, step S3 to be described later is not
performed until a thermal equilibrium is achieved between the optical waveguide circuit
10 and the sample 21. After the thermal equilibrium is achieved between the optical
waveguide circuit 10 and the sample 21, the non-invasive substance analyzer 1 is used
to analyze the substance in the sample 21 or on the surface of the sample 21.
25 [0037] The non-invasive substance analysis method of the present embodiment includes
measuring the first intensity of the first light 27a incident on the light intensity detector
30 without irradiating the sample 21 with the excitation light 24 (S3). Since the sample
21 is not irradiated with the excitation light 24 (an OFF state of the excitation light 24),
absorption heat is not generated in the sample 21.
- 13 -
[0038] The non-invasive substance analysis method of the present embodiment includes
measuring the second intensity of the first light 27a incident on the light intensity detector
30 while irradiating the sample 21 with the excitation light 24 (S4). Since the sample
21 is irradiated with the excitation light 24 (an ON state of the excitation light 24), the
5 excitation light 24 is absorbed by the substance in the sample 21 or on the surface of the
sample 21. Absorption heat is generated in the sample 21. The absorption heat in the
sample 21 is conducted to the waveguide-type ring resonator 12. The temperature of
the waveguide-type ring resonator 12 changes, and thereby the refractive index of the
waveguide-type ring resonator 12 changes. Accordingly, the coupling rate of the probe
10 light 27 from the first optical waveguide 11 to the second optical waveguide 13 via the
waveguide-type ring resonator 12 changes. Therefore, the second intensity of the first
light 27a is different from the first intensity of the first light 27a.
[0039] The non-invasive substance analysis method of the present embodiment includes
determining the amount or concentration of the substance in the sample 21 or on the
15 surface of the sample 21 from the first intensity of the first light 27a and the second
intensity of the first light 27a (S5). For example, the substance analysis unit 33 is
connected to a memory (not shown). The memory stores a data table in which the
wavelength of the excitation light 24 is associated with the type of the substance, and a
data table in which the difference between the first intensity and the second intensity is
20 associated with the amount or concentration of the substance. The substance analysis
unit 33 determines the type of the substance, and calculates the amount or concentration
of the substance with reference to these data tables.
[0040] Effects of the non-invasive substance analyzer 1 of the present embodiment will
be described.
25 The non-invasive substance analyzer 1 of the present embodiment includes an
optical waveguide circuit 10, an excitation light source 23, a probe light source 26, and
a first light intensity detector (a light intensity detector 30). The optical waveguide
circuit 10 has a first main surface (a main surface 10a) including a sample mounting
region 19 and a second main surface (a main surface 10b) opposite to the first main
- 14 -
surface. The excitation light source 23 emits excitation light 24 toward a sample 21
mounted on the sample mounting region 19. The probe light source 26 emits probe
light 27. The optical waveguide circuit 10 includes a first optical waveguide 11 to
which the probe light 27 is incident, a waveguide-type ring resonator 12 which is
5 optically coupled to the first optical waveguide 11, and a second optical waveguide 13
which is optically coupled to the waveguide-type ring resonator 12. The first light
intensity detector is optically coupled to the second optical waveguide 13, and detects
the intensity of the first light 27a which is a part of the probe light 27 and is optically
coupled to the second optical waveguide 13.
10 [0041] The first light intensity detector (the light intensity detector 30) detects a change
in the intensity of the first light 27a coupled to the second optical waveguide 13 due to
the ON/OFF of the excitation light 24 instead of a change in the position of the probe
light 27 due to the ON/OFF of the excitation light 24. Therefore, the first light intensity
detector is miniaturized, and thereby the non-invasive substance analyzer 1 is
15 miniaturized.
[0042] In the non-invasive substance analyzer 1 of the present embodiment, the sample
mounting region 19 is located inside the waveguide-type ring resonator 12 in a plan view
of the first main surface (the main surface 10a).
[0043] In a plan view of the first main surface (the main surface 10a), the sample
20 mounting region 19 is surrounded by the waveguide-type ring resonator 12. The
absorption heat in the sample 21 is efficiently conducted to the waveguide-type ring
resonator 12. The change in the intensity of the first light 27a due to the ON/OFF of
the excitation light 24 becomes greater. Therefore, the non-invasive substance analyzer
1 can analyze the substance in the sample 21 or on the surface of the sample 21 with
25 higher accuracy.
[0044] The non-invasive substance analyzer 1 according to the present embodiment
further includes a substance analysis unit 33 that analyzes a substance in the sample 21
or on the surface of the sample 21 based on the intensity of the first light 27a. Therefore,
the non-invasive substance analyzer 1 is miniaturized.
- 15 -
[0045] In the non-invasive substance analyzer 1 of the present embodiment, the optical
waveguide circuit 10 includes a first termination portion (a termination portion 17).
The second optical waveguide 13 includes a first end (an end 13a) optically coupled to
the first light intensity detector (the light intensity detector 30) and a second end (an end
5 13b) opposite to the first end. The first termination portion is provided at the second
end of the second optical waveguide 13, and scatters or absorbs the probe light 27.
[0046] The first termination portion (the termination portion 17) scatters or absorbs the
probe light 27 to prevent the return light of the probe light 27 from being coupled to the
waveguide-type ring resonator 12, the probe light source 26, and the first light intensity
10 detector (the light intensity detector 30). Therefore, the non-invasive substance
analyzer 1 can analyze the substance in the sample 21 or on the surface of the sample 21
with higher accuracy.
[0047] In the non-invasive substance analyzer 1 of the present embodiment, the optical
waveguide circuit 10 includes a second termination portion (a termination portion 16).
15 The first optical waveguide 11 includes a third end (an end 11a) to which the probe light
27 is incident and a fourth end (an end 11b) opposite to the third end. The second
termination portion is provided at the fourth end of the first optical waveguide 11, and
scatters or absorbs the probe light 27.
[0048] The second termination portion (the termination portion 16) scatters or absorbs
20 the probe light 27 to prevent the return light of the probe light 27 from being coupled to
the waveguide-type ring resonator 12, the probe light source 26, and the first light
intensity detector (the light intensity detector 30). Therefore, the non-invasive
substance analyzer 1 can analyze the substance in the sample 21 or on the surface of the
sample 21 with higher accuracy.
25 [0049] In the non-invasive substance analyzer 1 of the present embodiment, the
waveguide-type ring resonator 12 is a silicon waveguide.
[0050] Silicon has a relatively large thermo-optical coefficient among optical materials
for optical waveguides. Therefore, even if the amount of absorption heat in the sample
21 is small due to reasons such as the amount of the substance in the sample 21 or on the
- 16 -
surface of the sample 21 is small, the change in the intensity of the first light 27a due to
the ON/OFF of the excitation light 24 becomes large. Thereby, the non-invasive
substance analyzer 1 can analyze the substance in the sample 21 or on the surface of the
sample 21 with higher accuracy.
5 [0051] Second Embodiment
A non-invasive substance analyzer 1b according to a second embodiment will be
described with reference to Fig. 6. The non-invasive substance analyzer 1b of the
present embodiment has a configuration similar to that of the non-invasive substance
analyzer 1 of the first embodiment, but is mainly different in the following points.
10 [0052] The non-invasive substance analyzer 1b includes a light intensity detector 37 in
place of the termination portion 16 (see Fig. 1). The light intensity detector 37 is
optically coupled to the end 11b of the first optical waveguide 11. The light intensity
detector 37 detects the intensity of the second light 27b which is a part of the probe light
27 and propagates in the first optical waveguide 11 without being coupled to the
15 waveguide-type ring resonator 12.
[0053] The non-invasive substance analyzer 1b analyzes the substance in the sample 21
or on the surface of the sample 21 based on the intensity of the first light 27a which is a
part of the probe light 27 and is optically coupled to the second optical waveguide 13 and
the intensity of the second light 27b which is a part of the probe light 27 and propagates
20 in the first optical waveguide 11 without being coupled to the waveguide-type ring
resonator 12. For example, the non-invasive substance analyzer 1b analyzes the
substance in the sample 21 or on the surface of the sample 21 based on a difference
between the intensity of the first light 27a which is a part of the probe light 27 and is
optically coupled to the second optical waveguide 13 and the intensity of the second light
25 27b which is a part of the probe light 27 and propagates in the first optical waveguide 11
without being coupled to the waveguide-type ring resonator 12.
[0054] Specifically, the light intensity detector 37 measures a third intensity of the
second light 27b incident on the light intensity detector 37 when the sample 21 is not
irradiated with the excitation light 24 and a fourth intensity of the second light 27b
- 17 -
incident on the light intensity detector 37 when the sample 21 is irradiated with the
excitation light 24. As described in the first embodiment, between a time when the
sample 21 is not irradiated with the excitation light 24 and a time when the sample 21 is
irradiated with the excitation light 24, the temperature of the waveguide-type ring
5 resonator 12 changes, which causes the coupling rate of the probe light 27 from the first
optical waveguide 11 to the second optical waveguide 13 via the waveguide-type ring
resonator 12 to change. Therefore, the fourth intensity of the second light 27b is
different from the third intensity of the second light 27b.
[0055] The light intensity detector 37 outputs the third intensity of the second light 27b
10 and the fourth intensity of the second light 27b to the substance analysis unit 33. The
light intensity detector 37 is, for example, a photodiode such as a SiGe photodiode. In
the present embodiment, the light intensity detector 37 is disposed on the substrate 15.
The light intensity detector 37 may be disposed outside the optical waveguide circuit 10.
[0056] The substance analysis unit 33 is also connected to a light intensity detector 37 in
15 addition to the light intensity detector 30. The substance analysis unit 33 receives the
first intensity of the first light 27a and the second intensity of the first light 27a from the
light intensity detector 30, and receives the third intensity of the second light 27b and the
fourth intensity of the second light 27b from the light intensity detector 37. The
substance analysis unit 33 determines the type, amount, or concentration of the substance
20 in the sample 21 or on the surface of the sample 21 from the first intensity of the first
light 27a, the second intensity of the first light 27a, the third intensity of the second light
27b, and the fourth intensity of the second light 27b.
[0057] A non-invasive substance analysis method of the present embodiment using the
non-invasive substance analyzer 1b will be described with reference mainly to Fig. 7.
25 The non-invasive substance analysis method of the present embodiment is similar to the
non-invasive substance analysis method of the first embodiment, but is different from
the non-invasive substance analysis method of the first embodiment in the following
points.
[0058] The non-invasive substance analysis method of the present embodiment includes,
- 18 -
subsequent to step S1, measuring the first intensity of the first light 27a incident on the
light intensity detector 30 and the third intensity of the second light 27b incident on the
light intensity detector 37 without irradiating the sample 21 with the excitation light 24
(S13). Since the sample 21 is not irradiated with the excitation light 24 (an OFF state
5 of the excitation light 24), absorption heat is not generated in the sample 21.
[0059] The non-invasive substance analysis method of the present embodiment includes
measuring the second intensity of the first light 27a incident on the light intensity detector
30 and the fourth intensity of the second light 27b incident on the light intensity detector
37 while irradiating the sample 21 with the excitation light 24 (S14). Since the sample
10 21 is irradiated with the excitation light 24 (an ON state of the excitation light 24), the
excitation light 24 is absorbed by the substance in the sample 21 or on the surface of the
sample 21. Absorption heat is generated in the sample 21. The absorption heat in the
sample 21 is conducted to the waveguide-type ring resonator 12. The temperature of
the waveguide-type ring resonator 12 changes, and thereby the refractive index of the
15 waveguide-type ring resonator 12 changes. Accordingly, the coupling rate of the probe
light 27 from the first optical waveguide 11 to the second optical waveguide 13 via the
waveguide-type ring resonator 12 changes. Therefore, the second intensity of the first
light 27a is different from the first intensity of the first light 27a. The fourth intensity
of the second light 27b is different from the third intensity of the second light 27b.
20 [0060] The non-invasive substance analysis method of the present embodiment includes
determining the amount or concentration of the substance in the sample 21 or on the
surface of the sample 21 from the first intensity of the first light 27a, the second intensity
of the first light 27a, the third intensity of the second light 27b, and the fourth intensity
of the second light 27b (S15). For example, the substance analysis unit 33 calculates a
25 difference between the first intensity of the first light 27a and the third intensity of the
second light 27b as a first difference signal when the excitation light 24 is turned off.
The substance analysis unit 33 calculates a difference between the second intensity of
the first light 27a and the fourth intensity of the second light 27b as a second difference
signal when the excitation light 24 is turned on. The memory stores a data table in
- 19 -
which the wavelength of the excitation light 24 is associated with the type of the
substance, and a data table in which a difference between the first difference signal and
the second difference signal is associated with the amount or concentration of the
substance. The substance analysis unit 33 determines the type of the substance and
5 calculates the amount or concentration of the substance with reference to these data tables.
[0061] The non-invasive substance analyzer 1b of the present embodiment further
exhibits the following effects in addition to the effects of the non-invasive substance
analyzer 1 of the first embodiment.
[0062] The non-invasive substance analyzer 1b of the present embodiment further
10 includes a second light intensity detector (a light intensity detector 37). The second
light intensity detector is optically coupled to the first optical waveguide 11, and detects
the intensity of the second light 27b which is a part of the probe light 27 and propagates
in the first optical waveguide 11 without being coupled to the waveguide-type ring
resonator 12.
15 [0063] The non-invasive substance analyzer 1b can analyze the substance in the sample
21 or on the surface of the sample 21 based on the difference between the intensity of the
first light 27a measured by the first light intensity detector (the light intensity detector
30) and the intensity of the second light 27b measured by the second light intensity
detector (the light intensity detector 37). The intensity of the first light 27a may include
20 a noise component due to a small disturbance in the optical waveguide circuit 10. The
small disturbance is, for example, roughness of a light incident surface of the optical
waveguide circuit 10 and roughness of a side wall of the optical waveguide due to a
manufacturing process. By determining the difference between the intensity of the first
light 27a and the intensity of the second light 27b, the noise component in the intensity
25 of the first light 27a is canceled by the noise component in the intensity of the second
light 27b. Therefore, the difference between the intensity of the first light 27a and the
intensity of the second light 27b has a higher S/N ratio than the intensity of the first light
27a. The non-invasive substance analyzer 1b can analyze the substance in the sample
21 or on the surface of the sample 21 with higher accuracy.
- 20 -
[0064] The non-invasive substance analyzer 1b of the present embodiment further
includes a substance analysis unit 33 that analyzes a substance in the sample 21 or on the
surface of the sample 21 based on a difference between the intensity of the first light 27a
and the intensity of the second light 27b.
5 [0065] By determing the difference between the intensity of the first light 27a and the
intensity of the second light 27b, the noise component in the intensity of the first light
27a is canceled by the noise component in the intensity of the second light 27b.
Therefore, the difference between the intensity of the first light 27a and the intensity of
the second light 27b has a higher S/N ratio than the intensity of the first light 27a. The
10 non-invasive substance analyzer 1b can analyze the substance in the sample 21 or on the
surface of the sample 21 with higher accuracy.
[0066] Third Embodiment
A non-invasive substance analyzer 1c according to a third embodiment will be
described with reference to Figs. 8 to 10. The non-invasive substance analyzer 1c of
15 the present embodiment has a configuration similar to that of the non-invasive substance
analyzer 1 of the first embodiment, but is mainly different in the following points.
[0067] With reference to Figs. 8 and 9, the non-invasive substance analyzer 1c of the
present embodiment includes a thermoregulator 40 that regulates a temperature of the
waveguide-type ring resonator 12. The thermoregulator 40 is, for example, a heater
20 such as a heater electrode. When a current is applied to the heater, the heater generates
heat to change the temperature of the waveguide-type ring resonator 12. The heater is
made of, for example, a high-resistance metal material such as tantalum, platinum, or
titanium. The thermoregulator 40 is disposed closer to the main surface 10a than the
waveguide-type ring resonator 12. The thermoregulator 40 is separated from the
25 waveguide-type ring resonator 12 by the cladding layer 14.
[0068] The thermoregulator 40 has a band shape along the circumferential direction of
the waveguide-type ring resonator 12 in a plan view of the main surface 10a. In the
plan view of the main surface 10a, the length of the thermoregulator 40 in the
circumferential direction of the waveguide-type ring resonator 12 is, for example, 50%
- 21 -
or less of the length of the waveguide-type ring resonator 12 in the circumferential
direction of the waveguide-type ring resonator 12. Therefore, the thermoregulator 40
is prevented from supplying excessive heat to the optical waveguide circuit 10 as
compared with the absorption heat in the sample 21. Thus, it is possible to prevent the
5 detection sensitivity of the absorption heat in the sample 21 from being significantly
reduced by the thermoregulator 40. The length of the thermoregulator 40 in the
circumferential direction of the waveguide-type ring resonator 12 may be 20% or less of
the length of the waveguide-type ring resonator 12 in the circumferential direction of the
waveguide-type ring resonator 12.
10 [0069] The phase of the waveguide-type ring resonator 12 is given by the equation (1)
of the first embodiment. Therefore, as illustrated in Fig. 10, when the thermoregulator
40 is used to regulate the temperature of the waveguide-type ring resonator 12, the initial
phase of the waveguide-type ring resonator 12 (the phase of the waveguide-type ring
resonator 12 when the excitation light 24 is turned off) changes. In the present
15 embodiment, the temperature of the thermoregulator 40 is set in such a manner that the
change in the intensity of the first light 27a due to the ON/OFF of the excitation light 24
becomes greater. Thus, the initial phase of the waveguide-type ring resonator 12 is set.
[0070] For example, with reference to Fig. 10, when the thermoregulator 40 is turned off,
the waveguide-type ring resonator 12 has an initial phase of p1. In the waveguide-type
20 ring resonator 12 having an initial phase of p1, the change in the coupling rate of the
probe light 27 from the first optical waveguide 11 to the waveguide-type ring resonator
12 due to the ON/OFF of the excitation light 24 is small, and thereby the change in the
intensity of the first light 27a due to the ON/OFF of the excitation light 24 is small.
[0071] The thermoregulator 40 is used to regulate the temperature of the waveguide-type
25 ring resonator 12 so as to set the initial phase of the waveguide-type ring resonator 12 to
p2. In the waveguide-type ring resonator 12 having an initial phase of p2, the change
in the coupling rate of the probe light 27 from the first optical waveguide 11 to the
waveguide-type ring resonator 12 due to the ON/OFF of the excitation light 24 becomes
greater, and thereby the change in the intensity of the first light 27a due to the ON/OFF
- 22 -
of the excitation light 24 becomes greater. Therefore, the absorption heat in the sample
21 can be detected with higher accuracy. Accordingly, the substance in the sample 21
or on the surface of the sample 21 can be analyzed with higher accuracy.
[0072] A non-invasive substance analysis method of the present embodiment using the
5 non-invasive substance analyzer 1c will be described with reference mainly to Fig. 11.
The non-invasive substance analysis method of the present embodiment is similar to the
non-invasive substance analysis method of the first embodiment (see Fig. 5), but is
different from the non-invasive substance analysis method of the first embodiment in the
following points.
10 [0073] The non-invasive substance analysis method according to the present
embodiment further includes regulating the initial phase of the waveguide-type ring
resonator 12 by using the thermoregulator 40 (S2) between step S1 and step S3.
Specifically, the intensity of the first light 27a is measured using the light intensity
detector 30 while changing the temperature of the waveguide-type ring resonator 12
15 using the thermoregulator 40 without irradiating the sample 21 with the excitation light
24. The temperature of the thermoregulator 40 is set in such a manner that a ratio of
the change in the intensity of the first light 27a to the change in the temperature of the
thermoregulator 40 (i.e., the change in the temperature of the waveguide-type ring
resonator 12) becomes greater, preferably the ratio becomes maximum. Thus, the
20 initial phase of the waveguide-type ring resonator 12 is set.
[0074] The non-invasive substance analyzer 1c of the present embodiment further
exhibits the following effects in addition to the effects of the non-invasive substance
analyzer 1 of the first embodiment.
[0075] The non-invasive substance analyzer 1c according to the present embodiment
25 further includes a thermoregulator 40 that regulates a temperature of the waveguide-type
ring resonator 12.
[0076] By regulating the temperature of the waveguide-type ring resonator 12 using the
thermoregulator 40, the initial phase of the waveguide-type ring resonator 12 (the phase
of the waveguide-type ring resonator 12 when the excitation light 24 is turned off) can
- 23 -
be set in such a manner that the change in the intensity of the first light 27a due to the
ON/OFF of the excitation light 24 becomes greater. Therefore, the substance in the
sample 21 or on the surface of the sample 21 can be analyzed with higher accuracy.
[0077] In the non-invasive substance analyzer 1c of the present embodiment, in a plan
5 view of the first main surface (the main surface 10a), the length of the thermoregulator
40 in the circumferential direction of the waveguide-type ring resonator 12 is 50% or less
of the length of the waveguide-type ring resonator 12 in the circumferential direction of
the waveguide-type ring resonator 12.
[0078] Therefore, the thermoregulator 40 is prevented from supplying excessive heat to
10 the optical waveguide circuit 10 as compared with the absorption heat in the sample 21.
Thus, it is possible to prevent the detection sensitivity of the absorption heat in the sample
21 from being significantly reduced by the thermoregulator 40. Therefore, the
substance in the sample 21 or on the surface of the sample 21 can be analyzed with higher
accuracy.
15 [0079] Fourth Embodiment
A non-invasive substance analyzer 1d according to a fourth embodiment will be
described with reference to Fig. 12. The non-invasive substance analyzer 1d of the
present embodiment has a configuration similar to that of the non-invasive substance
analyzer 1 of the first embodiment, but is mainly different in the following points.
20 [0080] The non-invasive substance analyzer 1d further includes a thermoregulator 42
that regulates a temperature of the probe light source 26. The thermoregulator 42 is, for
example, a heater or a Peltier element. When the temperature of the probe light source
26 is changed by the thermoregulator 42, the wavelength of the probe light 27 emitted
from the probe light source 26 changes.
25 [0081] Since the phase of the waveguide-type ring resonator 12 is given by the equation
(1) of the first embodiment, when the wavelength of the probe light 27 changes, the initial
phase of the waveguide-type ring resonator 12 (the phase of the waveguide-type ring
resonator 12 when the excitation light 24 is turned off) changes. In the present
embodiment, the thermoregulator 42 is used to regulate the temperature of the probe light
- 24 -
source 26 so as to regulate the wavelength of the probe light 27. The wavelength of the
probe light 27 is set in such a manner that the change in the intensity of the first light 27a
due to the ON/OFF of the excitation light 24 becomes greater. Thus, the initial phase
of the waveguide-type ring resonator 12 is set.
5 [0082] The non-invasive substance analyzer 1d of the present embodiment further
exhibits the following effects in addition to the effects of the non-invasive substance
analyzer 1 of the first embodiment.
[0083] The non-invasive substance analyzer 1d of the present embodiment further
includes a thermoregulator 42 that regulates a temperature of the probe light source 26.
10 [0084] The thermoregulator 42 is used to regulate the temperature of the probe light
source 26 so as to regulate the wavelength of the probe light 27. By regulating the
wavelength of the probe light 27, the initial phase of the waveguide-type ring resonator
12 (the phase of the waveguide-type ring resonator 12 when the excitation light 24 is
turned off) can be set in such a manner that the change in the intensity of the first light
15 27a due to the ON/OFF of the excitation light 24 becomes greater. Thus, the substance
in the sample 21 or on the surface of the sample 21 can be analyzed with higher accuracy.
[0085] Fifth Embodiment
A non-invasive substance analyzer 1e according to a fifth embodiment will be
described with reference to Figs. 13 and 14. The non-invasive substance analyzer 1e of
20 the present embodiment has a configuration similar to that of the non-invasive substance
analyzer 1 of the first embodiment, but is mainly different in the following points.
[0086] In the present embodiment, the optical waveguide circuit 10 is provided with a
recess 15c on a surface 15a of the substrate 15 facing the waveguide-type ring resonator
12. The recess 15c faces the waveguide-type ring resonator 12 in the thickness
25 direction of the optical waveguide circuit 10 (the direction in which the main surface 10a
and the main surface 10b face each other). The recess 15c is formed by cutting or
etching the substrate 15. In a plan view of the main surface 10a, the recess 15c overlaps
with the waveguide-type ring resonator 12.
[0087] The optical waveguide circuit 10 includes a thermal insulation member 44. The
- 25 -
recess 15c is filled with the thermal insulation member 44. The thermal insulation
member 44 has a smaller thermal conductivity than the substrate 15. In the present
embodiment, the thermal insulation member 44 is made of the same material (for
example, silica glass) as that of the cladding layer 14. The thermal insulation member
5 44 may be made of a material having a smaller thermal conductivity than the substrate
15, and may be made of a material different from that of the cladding layer 14. The
thermal insulation member 44 faces the waveguide-type ring resonator 12 in the
thickness direction of the optical waveguide circuit 10 (the direction in which the main
surface 10a and the main surface 10b face each other).
10 [0088] The non-invasive substance analyzer 1e of the present embodiment further
exhibits the following effects in addition to the effects of the non-invasive substance
analyzer 1 of the first embodiment.
[0089] In the non-invasive substance analyzer 1e of the present embodiment, the optical
waveguide circuit 10 includes a substrate 15 which supports the waveguide-type ring
15 resonator 12 and a thermal insulation member 44 which has a smaller thermal
conductivity than the substrate 15. A recess 15c that overlaps with the waveguide-type
ring resonator 12 in a plan view of the first main surface (main surface 10a) is provided
on a surface 15a of the substrate 15 facing the waveguide-type ring resonator 12. The
recess 15c is filled with the thermal insulation member 44.
20 [0090] The thermal insulation member 44 makes it difficult for the absorption heat in the
sample 21 to escape to the substrate 15. The change in the intensity of the first light
27a due to the ON/OFF of the excitation light 24 becomes greater. Therefore, the noninvasive substance analyzer 1e can analyze the substance in the sample 21 or on the
surface of the sample 21 with higher accuracy.
25 [0091] Sixth Embodiment
A non-invasive substance analyzer 1f according to a sixth embodiment will be
described with reference to Figs. 15 and 16. The non-invasive substance analyzer 1f of
the present embodiment has a configuration similar to that of the non-invasive substance
analyzer 1 of the first embodiment, but is mainly different in the following points.
- 26 -
[0092] In the non-invasive substance analyzer 1f, a through hole 46 is provided in the
optical waveguide circuit 10. The through hole 46 extends from the sample mounting
region 19 to the main surface 10b and penetrates the optical waveguide circuit 10. The
through hole 46 is located inside the waveguide-type ring resonator 12. The excitation
5 light 24 passes through the through hole 46, and is irradiated on the sample 21. In the
present embodiment, in a plan view of the main surface 10a, the size of the sample 21 is
larger than the size of the through hole 46.
[0093] The non-invasive substance analyzer 1f of the present embodiment further
exhibits the following effects in addition to the effects of the non-invasive substance
10 analyzer 1 of the first embodiment.
[0094] In the non-invasive substance analyzer 1f of the present embodiment, a through
hole 46 that extends from the sample mounting region 19 to the second main surface (the
main surface 10b) is provided in the optical waveguide circuit 10. The excitation light
24 passes through the through hole 46, and is irradiated on the sample 21.
15 [0095] The through hole 46 through which the excitation light 24 passes is provided in
the optical waveguide circuit 10. Therefore, the excitation light 24 is not absorbed by
the optical waveguide circuit 10, and thereby reaches the sample 21 with stronger light
intensity. The absorption heat in the sample 21 increases. In addition, it is difficult
for the absorption heat in the sample 21 to escape in the thickness direction of the optical
20 waveguide circuit 10 (the direction in which the main surface 10a and the main surface
10b face each other). The change in the intensity of the first light 27a due to the
ON/OFF of the excitation light 24 becomes greater. Therefore, the substance in the
sample 21 or on the surface of the sample 21 can be analyzed with higher accuracy.
[0096] Even if the optical waveguide circuit 10 (the substrate 15) is made of a material
25 opaque to the excitation light 24, the excitation light 24 can be irradiated toward the
sample 21 from the side of the main surface 10b. This expands the choice of materials
for the optical waveguide circuit 10 (the substrate 15) and increases the degree of
freedom of arranging the excitation light source 23.
[0097] Seventh Embodiment
- 27 -
A non-invasive substance analyzer 1g according to a seventh embodiment will be
described with reference to Figs. 17 and 18. The non-invasive substance analyzer 1g
of the present embodiment has a configuration similar to that of the non-invasive
substance analyzer 1f of the sixth embodiment, but is mainly different in the following
5 points.
[0098] The non-invasive substance analyzer 1g further includes an optical medium 50.
The optical medium 50 transmits the excitation light 24. The transmittance of the
optical medium 50 with respect to the excitation light 24 is greater than the transmittance
of the optical waveguide circuit 10 (the substrate 15) with respect to the excitation light
10 24. The excitation light 24 passes through the optical medium 50, and is irradiated on
the sample 21. When the excitation light 24 is mid-infrared light, the optical medium
50 is made of a material transparent to the mid-infrared light, such as germanium (Ge),
zinc selenide (ZnSe), zinc sulfide (ZnS), or chalcogenide glass (SSbSnGe).
[0099] The optical medium 50 closes the through hole 46. At least a part of the sample
15 mounting region 19 is formed by the optical medium 50. The sample 21 may be
mounted on the optical medium 50. The through hole 46 is filled with the optical
medium 50. The optical medium 50 extends from the sample mounting region 19 to
the main surface 10b. The thermal conductivity of the optical medium 50 is greater
than the thermal conductivity of air. Therefore, the absorption heat in the sample 21 is
20 efficiently conducted to the waveguide-type ring resonator 12 through the optical
medium 50. The thermal conductivity of the optical medium 50 may be greater than
the thermal conductivity of the cladding layer 14. The thermal conductivity of the
optical medium 50 is smaller than the thermal conductivity of the substrate 15.
Therefore, it is difficult for the absorption heat in the sample 21 to escape in the thickness
25 direction of the optical waveguide circuit 10 (the direction in which the main surface 10a
and the main surface 10b face each other).
[0100] With reference to Fig. 19, in a modification of the present embodiment, the
optical medium 50 extends from sample mounting region 19 to a height of an inner side
surface 12a of the waveguide-type ring resonator 12 in the thickness direction of the
- 28 -
optical waveguide circuit 10 (the direction in which the main surface 10a and the main
surface 10b face each other). In other words, the optical medium 50 faces at least a part
of the inner side surface 12a of the waveguide-type ring resonator 12. The optical
medium 50 may extend from the sample mounting region 19 to a height of a lower
5 surface 12b of the waveguide-type ring resonator 12 in the thickness direction of the
optical waveguide circuit 10. In other words, the optical medium 50 may face the entire
inner side surface 12a of the waveguide-type ring resonator 12. The lower surface 12b
of the waveguide-type ring resonator 12 faces the main surface 10b.
[0101] A portion of the through hole 46 that is closer to the main surface 10b than the
10 optical medium 50 is a cavity that is not filled with the optical medium 50. The
excitation light 24 passes through the cavity and the optical medium 50, and is irradiated
on the sample 21. The optical medium 50 is separated from the substrate 15, which
makes it difficult for the absorption heat in the sample 21 to escape to the substrate 15
through the optical medium 50. Therefore, the optical medium 50 may be made of a
15 material having a greater thermal conductivity than the cladding layer 14. For example,
the optical medium 50 may be made of a material having a thermal conductivity of 10
W/(m·K) or more, such as germanium (Ge), zinc selenide (ZnSe), or zinc sulfide (ZnS).
Therefore, the absorption heat in the sample 21 is efficiently conducted to the waveguidetype ring resonator 12 through the optical medium 50.
20 [0102] The non-invasive substance analyzer 1g of the present embodiment further
exhibits the following effects similar to the effects of the non-invasive substance analyzer
1f of the sixth embodiment.
[0103] The non-invasive substance analyzer 1g of the present embodiment further
includes an optical medium 50 that transmits the excitation light 24. The optical
25 medium 50 closes the through hole 46. The excitation light 24 passes through the
optical medium 50, and is irradiated on the sample 21.
[0104] Since the excitation light 24 passes through the optical medium 50, it reaches the
sample 21 with stronger light intensity. The absorption heat in the sample 21 is
efficiently conducted to the waveguide-type ring resonator 12 through the optical
- 29 -
medium 50. The change in the intensity of the first light 27a due to the ON/OFF of the
excitation light 24 becomes greater. Therefore, the substance in the sample 21 or on
the surface of the sample 21 can be analyzed with higher accuracy.
[0105] The sample 21 may be mounted on the optical medium 50. Thus, the substance
5 in the sample 21 or on the surface of the sample 21 can be analyzed even if the size of
the sample 21 is smaller than the size of the through hole 46 or even if the sample 21 is
liquid.
[0106] In the non-invasive substance analyzer 1g of the present embodiment, the optical
medium 50 extends from the sample mounting region 19 to the height of the inner side
10 surface 12a of the waveguide-type ring resonator 12. A portion of the through hole 46
that is closer to the second main surface (the main surface 10b) than the optical medium
50 is a cavity that is not filled with the optical medium 50.
[0107] Since the excitation light 24 is not attenuated in the cavity, the excitation light 24
reaches the sample 21 with stronger light intensity. The absorption heat in the sample
15 21 increases. In addition, since the thermal conductivity of air in the cavity is low, the
cavity makes it difficult for the absorption heat in the sample 21 to escape from the
waveguide-type ring resonator 12. Therefore, the change in the intensity of the first
light 27a due to ON/OFF of the excitation light 24 becomes greater. Therefore, the
substance in the sample 21 or on the surface of the sample 21 can be analyzed with higher
20 accuracy.
[0108] Eighth Embodiment
A non-invasive substance analyzer 1h according to an eighth embodiment will be
described with reference to Figs. 20 and 21. The non-invasive substance analyzer 1h
of the present embodiment has a configuration similar to that of the non-invasive
25 substance analyzer 1g of the seventh embodiment, but is mainly different in the following
points.
[0109] The non-invasive substance analyzer 1h of the present embodiment includes a
first optical medium 51 and a second optical medium 52 instead of the optical medium
50. The first optical medium 51 and the second optical medium 52 transmit the
- 30 -
excitation light 24. The transmittance of the first optical medium 51 with respect to the
excitation light 24 is greater than the transmittance of the optical waveguide circuit 10
(specifically the substrate 15) with respect to the excitation light 24. The transmittance
of the second optical medium 52 with respect to the excitation light 24 is greater than the
5 transmittance of the optical waveguide circuit 10 (specifically the substrate 15) with
respect to the excitation light 24. The first optical medium 51 closes the through hole
46. The second optical medium 52 closes the through hole 46. The second optical
medium 52 is disposed closer to the sample mounting region 19 than the first optical
medium 51. At least a part of the sample mounting region 19 is formed by the second
10 optical medium 52. The sample 21 may be mounted on the second optical medium 52.
The excitation light 24 passes through the first optical medium 51 and the second optical
medium 52, and is irradiated on the sample 21.
[0110] The first optical medium 51 has a lower thermal conductivity than the second
optical medium 52. The first optical medium 51 separates the second optical medium
15 52 from the substrate 15. Therefore, it is difficult for the absorption heat in the sample
21 to escape in the thickness direction of the optical waveguide circuit 10. The first
optical medium 51 may have, for example, a thermal conductivity of 5 W/(m·K) or less,
or may have a thermal conductivity of 1 W/(m·K) or less. When the excitation light 24
is mid-infrared light, the first optical medium 51 is made of, for example, chalcogenide
20 glass (SSbSnGe).
[0111] The second optical medium 52 has a higher thermal conductivity than the first
optical medium 51. Therefore, the absorption heat in the sample 21 is efficiently
conducted to the waveguide-type ring resonator 12 through the second optical medium
52. Since the second optical medium 52 is separated from the substrate 15, it is difficult
25 for the absorption heat in the sample 21 to escape to the substrate 15. Therefore, the
second optical medium 52 may be made of a material having a greater thermal
conductivity than the cladding layer 14. For example, the second optical medium 52
may have a thermal conductivity of 10 W/(m·K) or more, or may have a thermal
conductivity of 15 W/(m·K) or more. When the excitation light 24 is mid-infrared light,
- 31 -
the second optical medium 52 is made of, for example, germanium (Ge), zinc selenide
(ZnSe), or zinc sulfide (ZnS).
[0112] The second optical medium 52 extends from the sample mounting region 19 to
the height of the inner side surface 12a of the waveguide-type ring resonator 12 in the
5 thickness direction of the optical waveguide circuit 10 (the direction in which the main
surface 10a and the main surface 10b face each other). In other words, the second
optical medium 52 faces at least a part of the inner side surface 12a of the waveguidetype ring resonator 12. The second optical medium 52 may extend from the sample
mounting region 19 to the height of the lower surface 12b of the waveguide-type ring
10 resonator 12 in the thickness direction of the optical waveguide circuit 10. In other
words, the second optical medium 52 may face the entire inner side surface 12a of the
waveguide-type ring resonator 12.
[0113] The non-invasive substance analyzer 1h of the present embodiment further
exhibits the following effects similar to the effects of the non-invasive substance analyzer
15 1g of the seventh embodiment.
[0114] The non-invasive substance analyzer 1h of the present embodiment further
includes a first optical medium 51 that transmits the excitation light 24 and a second
optical medium 52 that transmits the excitation light 24. The first optical medium 51
closes the through hole 46. The second optical medium 52 closes the through hole 46,
20 has a higher thermal conductivity than the first optical medium 51, and is disposed closer
to the sample mounting region 19 than the first optical medium 51. The excitation light
24 passes through the first optical medium 51 and the second optical medium 52, and is
irradiated on the sample 21.
[0115] The absorption heat in the sample 21 is efficiently conducted to the waveguide25 type ring resonator 12 through the second optical medium 52. However, the first optical
medium 51 makes it difficult for the absorption heat in the sample 21 to escape from the
waveguide-type ring resonator 12. The change in the intensity of the first light 27a due
to the ON/OFF of the excitation light 24 becomes greater. Therefore, the substance in
the sample 21 or on the surface of the sample 21 can be analyzed with higher accuracy.
- 32 -
[0116] The sample 21 may be mounted on the second optical medium 52. Thus, the
substance in the sample 21 or on the surface of the sample 21 can be analyzed even if the
size of the sample 21 is smaller than the size of the through hole 46 or even if the sample
21 is liquid.
5 [0117] In the non-invasive substance analyzer 1h of the present embodiment, the second
optical medium 52 extends from the sample mounting region 19 to the height of the inner
side surface 12a of the waveguide-type ring resonator 12.
[0118] The absorption heat in the sample 21 is more efficiently conducted to the
waveguide-type ring resonator 12 through the optical medium 50. Therefore, the
10 change in the intensity of the first light 27a due to ON/OFF of the excitation light 24
becomes greater. Therefore, the substance in the sample 21 or on the surface of the
sample 21 can be analyzed with higher accuracy.
[0119] In the non-invasive substance analyzer 1h of the present embodiment, the second
optical medium 52 extends from the sample mounting region 19 to the height of the lower
15 surface 12b of the waveguide-type ring resonator 12. The lower surface 12b of the
waveguide-type ring resonator 12 faces the second main surface (the main surface 10b).
[0120] The absorption heat in the sample 21 is more efficiently conducted to the
waveguide-type ring resonator 12 through the optical medium 50. Therefore, the
change in the intensity of the first light 27a due to ON/OFF of the excitation light 24
20 becomes greater. Therefore, the substance in the sample 21 or on the surface of the
sample 21 can be analyzed with higher accuracy.
[0121] It should be understood that the first to eighth embodiments disclosed herein are
illustrative and non-restrictive in all respects. At least two of the first to eighth
embodiments disclosed herein may be combined as long as there is no contradiction.
25 The scope of the present disclosure is defined the claims rather than the above description,
and is intended to include all modifications within the meaning and scope equivalent to
the claims.
- 33 -
REFERENCE SIGNS LIST
[0122] 1, 1b, 1c, 1d, 1e, 1f, 1g, 1h: non-invasive substance analyzer; 10: optical
waveguide circuit; 10a, 10b: main surface; 11: first optical waveguide; 11a, 11b,
13a, 13b: end; 12: waveguide-type ring resonator; 12a: inner side surface; 12b:
5 lower surface; 13: second optical waveguide; 14: cladding layer; 15: substrate;
15a: surface; 15c: recess; 16, 17: termination portion; 19: sample mounting region;
21: sample; 23: excitation light source; 24: excitation light; 26: probe light source;
27: probe light; 27a: first light; 27b: second light; 30, 37: light intensity detector;
33: substance analyzer; 40, 42: thermoregulator; 44: thermal insulation member;
10 46: through hole; 50: optical medium; 51: first optical medium; 52: second optical
medium.

WE CLAIM:
[Claim 1] A non-invasive substance analyzer comprising:
an optical waveguide circuit having a first main surface including a sample
5 mounting region and a second main surface opposite to the first main surface;
an excitation light source that emits excitation light toward a sample mounted on
the sample mounting region;
a probe light source that emits probe light; and
a first light intensity detector,
10 wherein the optical waveguide circuit includes a first optical waveguide to which
the probe light is incident, a waveguide-type ring resonator which is optically coupled to
the first optical waveguide, and a second optical waveguide which is optically coupled
to the waveguide-type ring resonator,
the first light intensity detector is optically coupled to the second optical
15 waveguide and detects an intensity of first light which is a part of the probe light and is
optically coupled to the second optical waveguide.
[Claim 2] The non-invasive substance analyzer according to claim 1, wherein
in a plan view of the first main surface, the sample mounting region is located
20 inside the waveguide-type ring resonator.
[Claim 3] The non-invasive substance analyzer according to claim 1 or claim 2
further comprising:
a substance analysis unit that analyzes a substance in the sample or on a surface
25 of the sample based on the intensity of the first light.
[Claim 4] The non-invasive substance analyzer according to claim 1 or claim 2,
further comprising:
a second light intensity detector,
- 35 -
wherein the second light intensity detector is optically coupled to the first optical
waveguide, and detects an intensity of second light which is a part of the probe light and
propagates in the first optical waveguide without being coupled to the waveguide-type
ring resonator.
5
[Claim 5] The non-invasive substance analyzer according to claim 4 further
comprising:
a substance analysis unit that analyzes a substance in the sample or on a surface
of the sample based on a difference between the intensity of the first light and the
10 intensity of the second light.
[Claim 6] The non-invasive substance analyzer according to claim 1 further
comprising:
a thermoregulator that regulates a temperature of the waveguide-type ring
15 resonator.
[Claim 7] The non-invasive substance analyzer according to claim 6, wherein
in a plan view of the first main surface, a length of the thermoregulator in a
circumferential direction of the waveguide-type ring resonator is 50% or less of a length
20 of the waveguide-type ring resonator in the circumferential direction.
[Claim 8] The non-invasive substance analyzer according to any one of claims
1 to 5 further comprising:
a thermoregulator that regulates a temperature of the probe light source.
25
[Claim 9] The non-invasive substance analyzer according to claim 1, wherein
the optical waveguide circuit includes a substrate which supports the waveguidetype ring resonator, and a thermal insulation member which has a smaller thermal
conductivity than the substrate,
- 36 -
a recess that overlaps with the waveguide-type ring resonator in a plan view of
the first main surface is provided on a surface of the substrate facing the waveguide-type
ring resonator, and
the recess is filled with the thermal insulation member.
5
[Claim 10] The non-invasive substance analyzer according to any one of claims
1 to 9, wherein
a through hole that extends from the sample mounting region to the second main
surface is provided in the optical waveguide circuit, and
10 the excitation light passes through the through hole, and is irradiated on the
sample.
[Claim 11] The non-invasive substance analyzer according to claim 10 further
comprising:
15 an optical medium that transmits the excitation light,
wherein the optical medium closes the through hole, and
the excitation light passes through the optical medium, and is irradiated on the
sample.
20 [Claim 12] The non-invasive substance analyzer according to claim 11, wherein
the optical medium extends from the sample mounting region to a height of an
inner side surface of the waveguide-type ring resonator, and
a portion of the through hole that is closer to the second main surface than the
optical medium is a cavity that is not filled with the optical medium.
25
[Claim 13] The non-invasive substance analyzer according to claim 10 further
comprising:
a first optical medium that transmits the excitation light; and
a second optical medium that transmits the excitation light,
- 37 -
wherein the first optical medium closes the through hole,
the second optical medium closes the through hole, has a higher thermal
conductivity than the first optical medium, and is disposed closer to the sample mounting
region than the first optical medium, and
5 the excitation light passes through the first optical medium and the second optical
medium, and is irradiated on the sample.
[Claim 14] The non-invasive substance analyzer according to claim 13, wherein
the second optical medium extends from the sample mounting region to a height
10 of an inner side surface of the waveguide-type ring resonator.
[Claim 15] The non-invasive substance analyzer according to claim 13, wherein
the second optical medium extends from the sample mounting region to a height
of a lower surface of the waveguide-type ring resonator, and
15 the lower surface of the waveguide-type ring resonator faces the second main
surface.
[Claim 16] The non-invasive substance analyzer according to any one of claims
1 to 3, wherein
20 the optical waveguide circuit includes a first termination portion,
the second optical waveguide includes a first end optically coupled to the first
light intensity detector and a second end opposite to the first end, and
the first termination portion is provided at the second end of the second optical
waveguide, and scatters or absorbs the probe light.
25
[Claim 17] The non-invasive substance analyzer according to claim 16, wherein
the optical waveguide circuit includes a second termination portion,
the first optical waveguide includes a third end to which the probe light is incident
and a fourth end opposite to the third end, and
- 38 -
the second termination portion is provided at the fourth end of the first optical
waveguide, and scatters or absorbs the probe light.
[Claim 18] The non-invasive substance analyzer according to any one of claims
5 1 to 17, wherein
the waveguide-type ring resonator is a silicon waveguide.