Claims:CLAIMS
We Claim:

1. An optical fiber (100) comprising:
a core region (108) defined by a core refractive index profile (200), wherein the core region (108) has a first core (102) defined by a first core refractive index (RI) profile (202) and a first core RI max (?peak) and a second core (104) defined by a second core RI profile (204) and a second core RI max (?core), wherein the first core RI max (?peak) is greater than the second core RI max (?core); and
a cladding region (106) surrounding the core region (108), wherein the cladding region (106) is defined by a cladding refractive index profile (400) and a cladding RI max (?clad), wherein the first core RI max (?peak) is greater than the second core RI max (?core) and the second core RI max (?core) is greater than the cladding RI max (?clad).

2. The optical fiber (100) as claimed in claim 1, wherein an absolute difference between the first core RI max (?peak) and the second core RI max (?core) is between 0.02 to 0.14.

3. The optical fiber (100) as claimed in claim 1, wherein the cladding region (106) further comprising a first cladding (110), a second cladding (112) and a third cladding (114), wherein the first cladding (110) and the third cladding (114) have pure silica and the second cladding (112) has down-doped silica.

4. The optical fiber (100) as claimed in claim 1, wherein a ratio of the second core RI max (?core) to the first core RI max (?peak) is in a range between 0.8 and 0.9.

5. The optical fiber (100) as claimed in claim 1, wherein the first core (102) and the second core (104) are up-doped.

6. The optical fiber (100) as claimed in claim 1, wherein each of the first core (102) and the second core (104) is defined by a radial dimension, wherein the radial dimension (R1) of the first core (102) is in a range between 0.5µm and 1.5µm and the radial dimension (R2) of the second core (104) is in a range between 4.4µm and 4.8µm.

7. The optical fiber (100) as claimed in claim 1, wherein each of a first cladding (110), a second cladding (112) and a third cladding (114) is defined by a radial dimension, wherein the radial dimension (R3) of the first cladding (110) is in a range of 7.5µm and 8.5µm, the radial dimension (R4) of the second cladding (112) is in a range of 12µm and 16µm and the radial dimension (R5) of the third cladding (114) is in a range of 45µm and 50.5µm.

8. The optical fiber (100) as claimed in claim 1, wherein the optical fiber (100) has a dispersion less than or equal to 18ps/nm-km at 1550nm wavelength, an MFD (mode field diameter) of 8.6±0.4µm at 1310nm wavelength and a cable cut-off wavelength of less than or equal to 1260nm.

9. The optical fiber (100) as claimed in claim 1, wherein the optical fiber (100) has:
a macro-bend loss of less than or equal to 0.03dB per 10 turns at 15mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.1dB per 10 turns at 15mm radius and at 1625nm wavelength;
a macro-bend loss of less than or equal to 0.1dB/turn at 10mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.2dB/turn at 10mm radius and at 1625nm wavelength; and
a macro-bend loss of less than or equal to 0.2dB/turn at 7.5mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.5dB/turn at 7.5mm radius and at 1625nm wavelength.

10. The optical fiber (100) as claimed in claim 1, wherein the optical fiber (100) has a Young's modulus for a primary coating layer (116) between 0.0002GPa and 0.0004GPa and a Young's modulus for a secondary coating layer (118) between 1.1Gpa and 1.7Gpa.

11. A method of manufacturing the optical fiber (100) comprising:
inserting a GeO2 doped glass rod (902) in a central hole of a soot preform (904);
drying the soot preform (904) and doping the soot preform (904) with fluorine;
sintering the soot preform (904) to convert the soot preform into a silica preform (908);
drawing a core rod (910) from the sintered silica preform (908);
over-cladding the core rod (910) with soot particles to form an optical fiber preform (912);
sintering the optical fiber preform (912); and
drawing the optical fiber (100) from the optical fiber preform (912).

12. The method as claimed in claim 11, wherein the GeO2 doped glass rod (902) is a central rod having a diameter in a range of 5mm-10 mm.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates to optical fibers, and in particular, relates to optical fibers with improved bend performance and manufacturing method thereof.

BACKGROUND
[0002] With the advancement of science and technology, various modern technologies are being employed for communication purposes. One of the most important modern communication technologies is optical fiber communication technology using a variety of optical fibers. An optical fiber is manufactured by an Outside Vapor Deposition (OVD) process. In the OVD process, a soot preform is deposited on a mandrel, wherein the mandrel revolves at a predetermined speed during deposition. Once the deposition process has been completed, the mandrel is removed and the soot preform is prepared. Due to the removal of the mandrel, the optical fiber drawn from a glass preform (which is prepared from the soot preform) has a refractive index profile with a center line dip as shown in a prior art reference “US6771865B2”. Because of the dip near a core region of the optical fiber, the bend performance of the optical fiber degrades, which further results in bend induced attenuation. In other words, the optical fiber of G657 category encounter bend performance failures and bend induced attenuation due to the center line dip.
[0003] Therefore, to control/reduce such bend induced attenuation and to improve bend performance, the central line dip of the optical fiber needs to be controlled in the OVD process.

OBJECT OF THE DISCLOSURE
[0004] A primary object of the present disclosure is to provide an optical fiber with improved bend performance and manufacturing method thereof.
[0005] Another object of the present disclosure is to reduce 30mm bend performance failure.
[0006] Another object of the present disclosure is to provide fluorinated refractive index profile with central peak for better bend performance, thereby reducing bend induced attenuation.

SUMMARY
[0007] Accordingly, an optical fiber with improved bend performance and manufacturing method thereof are provided.
[0008] The optical fiber comprises a core region defined by a core refractive index profile and a cladding region surrounding the core region, wherein the cladding region is defined by a cladding refractive index profile. The core region has a first core defined by a first core refractive index (RI) profile and a first core RI max and a second core defined by a second core RI profile and a second core RI max, wherein the first core RI max is greater than the second core RI max and the first core RI max is greater than rest of refractive indices. The core region (i.e., the first core and the second core) is up-doped with germanium oxide (GeO2). The GeO2 doping results in centreline peak that helps in improving bend performance as compared to existing centreline dip OVD fiber profile, results in better confinement of light at the center of the core region and reduces an M-bend failure percentage.
[0009] The cladding region further comprises a first cladding, a second cladding and a third cladding, wherein the first cladding and the third cladding are composed of pure silica and the second cladding is composed of a down-doped silica. The down-dopant is fluorine. The cladding region is defined by a cladding refractive index profile and a cladding RI max (?clad), wherein the first core RI max (?peak) is greater than the second core RI max (?core) and the second core RI max (?core) is greater than the cladding RI max (?clad). The optical fiber further has a primary coating layer and a secondary coating layer.
[0010] The optical fiber has a macro-bend loss of less than or equal to 0.03dB per 10 turns at 15mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.1dB per 10 turns at 15mm radius and at 1625nm wavelength. Further, the optical fiber has a macro-bend loss of less than or equal to 0.1dB/turn at 10mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.2dB/turn at 10mm radius and at 1625nm wavelength. Furthermore, the optical fiber has a macro-bend loss of less than or equal to 0.2dB/turn at 7.5mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.5dB/turn at 7.5mm radius and at 1625nm wavelength.
[0011] The optical fiber is manufactured by inserting a GeO2 doped glass rod in a central hole of a soot preform, drying the soot preform and doping the soot preform with fluorine, sintering the soot preform to convert the soot preform into a silica preform, drawing a core rod from the sintered silica preform, over-cladding the core rod with soot particles to form an optical fiber preform and sintering the optical fiber preform from which the optical fiber is drawn.
[0012] These and other aspects herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the invention herein without departing from the spirit thereof.

BRIEF DESCRIPTION OF FIGURE
[0013] The invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the drawings. The invention herein will be better understood from the following description with reference to the drawings, in which:
[0014] FIG. 1 illustrates a cross-sectional view of an optical fiber depicting a core region having a first core and a second core; and a cladding region.
[0015] FIG. 2 illustrates a refractive index profile of the core region of the optical fiber.
[0016] FIG. 3 illustrates a cross-sectional view of the optical fiber depicting the core region and the cladding region having a first cladding, a second cladding and a third cladding.
[0017] FIG. 4 illustrates a refractive index profile of the cladding region of the optical fiber.
[0018] FIG. 5 illustrates a cross-sectional view of the optical fiber having the core region, the cladding region, a primary coating layer and a secondary coating layer.
[0019] FIG. 6 illustrates a cross-sectional view of the optical fiber having the first core, the second core, the first cladding, the second cladding and the third cladding.
[0020] FIG. 7 illustrates a refractive index profile of the optical fiber having the first core, the second core, the first cladding, the second cladding and the third cladding.
[0021] FIG. 8 illustrates a cross-sectional view of the optical fiber having the first core, the second core, the first cladding, the second cladding, the third cladding, the primary coating layer and the secondary coating layer.
[0022] FIG. 9 illustrates a process of manufacturing the optical fiber.
[0023] FIG. 10 is a flow chart depicting a method of manufacturing the optical fiber.
[0024] It should be noted that the accompanying figures are intended to present illustrations of few examples of the present disclosure. The figures are not intended to limit the scope of the present disclosure. It should also be noted that accompanying figures are not necessarily drawn to scale.

DETAILED DESCRIPTION
[0025] In the following detailed description of the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be obvious to a person skilled in the art that the invention may be practiced with or without these specific details. In other instances, well known methods, procedures and components have not been described in details so as not to unnecessarily obscure aspects of the invention.
[0026] Furthermore, it will be clear that the invention is not limited to these alternatives only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art, without parting from the scope of the invention.
[0027] The accompanying drawings are used to help easily understand various technical features and it should be understood that the alternatives presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.
[0028] Unlike conventional optical fibers, the present disclosure proposes an optical fiber with improved bend performance and manufacturing method thereof that solves the problem of bend performance failure. The same is achieved by developing an optical fiber having a refractive index profile with a central (or centreline) peak.
[0029] Now, simultaneous reference is made to FIG. 1 through FIG. 8, in which FIG. 1 illustrates a cross-sectional view of an optical fiber 100 depicting a core region 108 having a first core 102 and a second core 104; and a cladding region 106, FIG. 2 illustrates a refractive index profile 200 of the core region 108 of the optical fiber 100, FIG. 3 illustrates a cross-sectional view of the optical fiber 100 depicting the core region 108 and the cladding region 106 having a first cladding 110, a second cladding 112 and a third cladding 114, FIG. 4 illustrates a refractive index profile 400 of the cladding region 106 of the optical fiber 100, FIG. 5 illustrates a cross-sectional view of the optical fiber 100 having the core region 108, the cladding region 106, a primary coating layer 116 and a secondary coating layer 118, FIG. 6 illustrates a cross-sectional view of the optical fiber 100 having the first core 102, the second core 104, the first cladding 110, the second cladding 112 and the third cladding 114, FIG. 7 illustrates a refractive index profile 700 of the optical fiber 100 having the first core 102, the second core 104, the first cladding 110, the second cladding 112 and the third cladding 114 and FIG. 8 illustrates a cross-sectional view of the optical fiber 100 having the first core 102, the second core 104, the first cladding 110, the second cladding 112, the third cladding 114, the primary coating layer 116 and the secondary coating layer 118.
[0030] In general, an optical fiber is a thin strand of glass or plastic or combination thereof capable of transmitting/propagating optical signals. The optical fiber 100 is configured to transmit information over long distances. The optical fiber 100 uses light to transmit voice and data communications over long distances when encapsulated in a jacket/sheath. The optical fiber 100 may be a bend insensitive fiber that has less degradation in optical properties or increment in optical attenuation during multiple winding/unwinding operations of an optical fiber cable. The optical fiber 100 may be defined by one or more cores and one or more claddings. Further, an up-dopant for e.g. Germanium may be added in the one or more cores, which helps in confinement of light within the one or more cores and the one or more claddings may either be kept un-doped or down-doped so as to avoid signal loss. Technically, this can be termed as difference in refractive index profiles of the one or more cores compared to the one or more claddings which helps in confinement of light within a stipulated core region.
[0031] Now referring to Figures, the optical fiber 100 comprises the core region 108 and the cladding region 106 surrounding the core region 108, wherein the core region 108 is the region in which optical signal is confined and the cladding region 106 is the region which prevents loss of signal by preventing any signal leakage from the core region 108. Such a structure of the core region 108 and the cladding region 106 is also termed as an optical waveguide.
[0032] The core region 108 may be defined by a core refractive index profile 200 as depicted in FIG. 2. The core region 108 may have the first core 102 and the second core 104. The first core 102 is a central core defined by a first core refractive index (RI) profile 202 and a first core refractive index max ?peak. Similarly, the second core 104 is a peripheral or annular core region defined by a second core RI profile 204 and a second core RI max ?core, where the second core 104 surrounds the first core 102. The first core RI max ?peak may be greater than the second core RI max ?core and the first core RI max ?peak may be greater than the rest of refractive indices. A ratio of the second core RI max ?core to the first core RI max ?peak is in a range between 0.8 and 0.9 and an absolute difference between the first core RI max ?peak and the second core RI max ?core is in a range between 0.02 to 0.14. Alternatively, the ratio of the second core RI max ?core to the first core RI max ?peak and the absolute difference between the first core RI max ?peak and the second core RI max ?core may vary.
[0033] The core region 108 may be composed of silica having up-dopant. The up-dopant is an additive for increasing a refractive index of silica. The up-dopant may be, but not limited to, germanium oxide (GeO2) and chlorine. Preferably, the up-dopant is germanium oxide (GeO2). The up-dopant concentration in the first core 102 and in the second core 104 may vary. The GeO2 doping results in centreline peak, i.e., the first core RI max ?peak that helps in improving bend performance as compared to existing centreline dip OVD fiber profile, results in better confinement of light at the center of the core region and reduces an M-bend failure percentage.
[0034] Each of the first core 102 and the second core 104 may be defined by a radial dimension. The radial dimension (R1) of the first core 102 may be in a range between 0.5µm and 1.5µm and the radial dimension (R2) of the second core 104 may be in a range between 4.4µm and 4.8µm. Alternatively, the radial dimension of the first core 102 and the second core 104 may vary.
[0035] The cladding region 106 may be defined by a cladding refractive index profile 400 as depicted in FIG. 4 and a cladding RI max ?clad, wherein the first core RI max ?peak is greater than the second core RI max ?core and the second core RI max ?core is greater than the cladding RI max ?clad. The cladding region 106 may further comprise the first cladding 110 surrounding the core region 108, the second cladding 112 surrounding the first cladding 110 and the third cladding 114 surrounding the second cladding 112 as depicted in FIG. 3, FIG. 6 and FIG. 8. The first cladding 110 may be a buffer cladding layer.
[0036] Each of the first cladding 110, the second cladding 112 and the third cladding 114 may be defined by a radial dimension. The radial dimension (R3) of the first cladding 110 may be in a range of 7.5µm and 8.5µm, the radial dimension (R4) of the second cladding 112 may be in a range of 12µm and 16µm and the radial dimension (R5) of the third cladding 114 may be in a range of 45µm and 50.5µm. Alternatively, the radial dimension of the first cladding 110, the second cladding 112 and the third cladding 114 may vary.
[0037] The first cladding 110 and the third cladding 114 may be composed of pure silica, therefore may be called as pure silica annular claddings, and the second cladding 112 may be composed of a down-doped silica, hence called as down-doped cladding trench. The down-dopant may be, but not limited to, fluorine and boron. Preferably, the down-dopant is fluorine. The down-dopant has propensity to lower the refractive index of the silica. Accordingly, the cladding region 106 may have a fluorinated trench/depression. That is, the second cladding 112 may have a fluorinated trench/depression defined by a thickness R4 – R3 (i.e., difference between the radial dimension (R4) of the second cladding 112 and the radial dimension (R3) of the first cladding 110.
[0038] The below Table 1 and Table 2 summarize the refractive index profile (centreline peak profile) 700 of the optical fiber 100 as shown in FIG. 7.
Table 1: Refractive Index Profile
SN First Core Second Core
R1 ?peak Alpha R2 ?core Alpha
1 0.5 0.52 2 4.4 0.43 5
2 0.91 0.50 1 4.7 0.45 6
3 1.5 0.53 3 4.5 0.42 8
4 1.07 0.48 1 4.8 0.4 4
MIN 0.5 0.48 1 4.4 0.4 4
MAX 1.5 0.52 3 4.8 0.45 8

Table 2: Refractive Index Profile
SN R3 Trench R5
R4 ?trench Alpha
1 7.95 16 -0.23 3 46.5
2 7.6 12 -0.25 4 50.5
3 7.7 13.5 -0.21 2 49
4 8.5 15 -0.22 3 47.5
MIN 7.5 12 -0.2 2 45
MAX 8.5 16 -0.25 4 50.5

[0039] Advantageously, the first core 102 has improved bend performance due to the first core RI max ?peak, which is also called as centreline peak, which gives better confinement of light in the first core 102 as effective refractive index will be greater than the effective refractive index of the centreline dip profile. Similarly, the second core 104 helps in achieving mode field diameter, zero dispersion, cable cut-off wavelength and macro-bend losses in a range explained below and the second cladding 112 improves bend insensitivity of the optical fiber 100.
[0040] The optical fiber 100 may be characterized by a dispersion less than or equal to 18ps/nm-km at 1550nm wavelength and an MFD (mode field diameter) of 8.6±0.4µm at 1310nm wavelength. In general, mode field diameter defines a section or area of optical fiber in which the optical signals travel and dispersion defines spreading of light pulse as its travels down the length of the optical fiber. Further, the optical fiber 100 may have a zero dispersion wavelength in a range of 1300nm and 1324nm.
[0041] The optical fiber 100 may have a macro-bend loss of less than or equal to 0.03dB per 10 turns at 15mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.1dB per 10 turns at 15mm radius and at 1625nm wavelength. The optical fiber 100 may have a macro-bend loss of less than or equal to 0.1dB/turn at 10mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.2dB/turn at 10mm radius and at 1625nm wavelength. Further, the optical fiber 100 may have a macro-bend loss of less than or equal to 0.2dB/turn at 7.5mm radius and at 1550nm wavelength and a macro-bend loss of less than or equal to 0.5dB/turn at 7.5mm radius and at 1625nm wavelength. The macro bend loss is defined by a loss occurred when an optical fiber cable is subjected to a significant amount of bending above a critical value of curvature.
[0042] The optical fiber 100 may be characterized by a cable cut-off wavelength of less than or equal to 1260nm. The cable cut-off wavelength is a minimum wavelength in which the optical fiber acts as a single mode fiber.
[0043] Alternatively, the cable cut-off, dispersion, zero dispersion wavelength, MFD and macro-bend loss may vary.
[0044] The optical fiber 100 may be coated with primary and secondary coatings as depicted in FIG. 5 and FIG. 8, where Young's modulus for the primary coating layer 116 is between 0.0002GPa and 0.0004GPa and Young's modulus for the secondary coating layer 118 is between 1.1Gpa and 1.7Gpa. Alternatively, the Young’s modulus may vary. The optical fiber 100 may have a diameter less than or equal to 250µm.
[0045] For the optical fiber having a diameter of 250µm, a diameter (2*R6) of the primary coating layer 116 (i.e., a primary diameter) may be between 180-200µm and a diameter (2*R7) of the secondary coating layer 118 (i.e., secondary diameter) may be between 240-247µm. Alternatively, for the optical fiber having a diameter of 200µm, a diameter of the primary coating layer (i.e., a primary diameter) may be between 150-170µm and a diameter of the secondary coating layer (i.e., secondary diameter) may be between 195-205µm with tolerance value.
[0046] Preferably, the optical fiber 100 disclosed herein is made by an outside vapor deposition (OVD) process familiar to the skilled artisan. Alternatively, other processes, which are known in the art, may be used to manufacture the optical fiber 100 disclosed herein.
[0047] FIG. 9 illustrates a process of manufacturing the optical fiber 100. The process includes inserting a GeO2 doped glass rod 902 in a central hole of a soot preform 904 and drying the soot preform 904 and doping the soot preform 904 with fluorine, wherein the GeO2 doped glass rod 902 is a central rod having a diameter in a range of 5mm-10 mm. Further, the process includes sintering the soot preform 904 in a draw furnace 906 to convert the soot preform into a silica preform 908 and drawing a core rod 910 from the sintered silica preform 908. The process further comprises over-cladding the core rod 910 with soot particles to form an optical fiber preform 912 and sintering the optical fiber preform 912 in the draw furnace 906 from which the optical fiber 100 is drawn.
[0048] FIG. 10 is a flow chart 1000 depicting a method of manufacturing the optical fiber 100. At step 1002, the method includes inserting the GeO2 doped glass rod 902 in the central hole of the soot preform 904, wherein the GeO2 doped glass rod 902 is a central rod having a diameter in a range of 5mm-10 mm. At step 1004, the method includes drying the soot preform 904 and doping the soot preform 904 with fluorine. At step 1006, the method includes sintering the soot preform 904 to convert the soot preform into a silica preform 908. At step 1008, the method includes drawing the core rod 910 from the sintered silica preform 908. At step 1010, the method comprises over-cladding the core rod 910 with soot particles to form the optical fiber preform 912. At step 1012, the method includes sintering the optical fiber preform 912. At step 1014, the method includes drawing the optical fiber 100 from the optical fiber preform 912.
[0049] Advantageously, the above method improves bend performance by removing centreline dip from existing optical fiber profiles.
[0050] It may be noted that the flow chart 1000 is explained to have above stated process steps; however, those skilled in the art would appreciate that the flow-chart 1000 may have more/less number of process steps which may enable all the above stated implementations of the present disclosure.
[0051] The various actions act, blocks, steps, or the like in the flow chart and sequence diagrams may be performed in the order presented, in a different order or simultaneously. Further, in some implementations, some of the actions, acts, blocks, steps, or the like may be omitted, added, modified, skipped, or the like without departing from the scope of the present disclosure.
[0052] It will be apparent to those skilled in the art that other alternatives of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention. While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific aspect, method, and examples herein. The invention should therefore not be limited by the above described alternative, method, and examples, but by all aspects and methods within the scope of the invention. It is intended that the specification and examples be considered as exemplary, with the true scope of the invention being indicated by the claims.
[0053] Conditional language used herein, such as, among others, "can," "may," "might," "may," “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain alternatives include, while other alternatives do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more alternatives or that one or more alternatives necessarily include logic for deciding, with or without other input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular alternative. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list.
[0054] Disjunctive language such as the phrase “at least one of X, Y, Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain alternatives require at least one of X, at least one of Y, or at least one of Z to each be present.
[0055] While the detailed description has shown, described, and pointed out novel features as applied to various alternatives, it can be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the scope of the disclosure. As can be recognized, certain alternatives described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others.