Fiber array units and methods

Abstract

A fiber array unit includes a substrate, a single mode fiber, and a polarization maintaining fiber. The substrate defines a first v-groove having a first depth and a second v-groove having a second depth different from the first depth. The single mode fiber is retained within the first v-groove of the substrate and has a substantially circular cross sectional shape. The polarization maintaining fiber is retained within the second v-groove of the substrate and has a cross sectional shape with non-circularity. The second depth is selected based on the non-circularity of the cross sectional shape.

Description

FIBER ARRAY UNITS AND METHODSRELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Application No. 63 / 649,719 filed on May 20, 2024. the content of which is relied upon and incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present specification generally relates to fiber array units and methods of manufacturing fiber array units.BACKGROUND

[0003] Fiber array units may include co-packaging of single mode fibers and polarization maintaining fibers. In particular, each of these fibers may be assembled within v- grooves of a substrate. The v-grooves of the substrate are commonly uniform in size.

[0004] However, single mode fibers and polarization maintaining fibers may have different cross sectional shapes due to the differences in structure of the fibers. For example, while single mode fibers may be substantially circular, polarization maintaining fibers may be more oblong or non-circular. This difference in cross sectional shape may create misalignment between the cores of the respective fibers when the v-grooves are uniform in size which may, in turn, decrease performance of the fiber array units.

[0005] Accordingly, a need exists for improved fiber array units and methods of manufacturing fiber array units to provide better core alignment for single mode and polarization maintaining fibers.SUMMARY

[0006] Additional features and advantages of the present disclosure will be set forth in the detailed description, which follows, and in part will be apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description, which follows the claims, as well as the appended drawings.

[0007] In one embodiment, a fiber array unit includes a substrate, a single mode fiber, and a polarization maintaining fiber. The substrate defines a first v-groove having a first depth and a second v-groove having a second depth different from the first depth. The single mode fiber is retained within the first v-groove of the substrate and has a substantially circular cross sectional shape. The polarization maintaining fiber is retained within the second v-groove of the substrate and has a cross sectional shape with non-circularity. The second depth is selected based on the non-circularity of the cross sectional shape.

[0008] In another embodiment, a method of manufacturing a fiber array unit includes machining a first v-groove of a substrate having a first depth, machining a second v-groove of the substrate having a second depth different from the first depth, aligning a single mode fiber within the first v-groove, and aligning a polarization maintaining fiber within the second v- groove. The polarization maintaining fiber has anon-circularity, and the machining the second v-groove includes selecting the second depth based on the non-circularity of the polarization maintaining fiber.

[0009] In yet another embodiment a fiber array unit includes a substrate, a single mode fiber, and a polarization maintaining fiber. The substrate includes a first v-groove having a first angle and a second v-groove having a second angle different from the first angle. The single mode fiber is retained within the first v-groove of the substrate and includes a substantially circular outer perimeter and a circular core. The polarization maintaining fiber is retained within the second v-groove of the substrate and includes a cross sectional shape having non- circularity and a single mode core. The second angle is selected based on the non-circularity of the polarization maintaining fiber such that the single mode core and the circular core are horizontally aligned.

[0010] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview' or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description, explain the principles and operations of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The embodiments set forth in the drawings are illustrative and exemplar}' in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

[0012] FIG. 1 schematically depicts a fiber array unit according to one or more embodiments shown and described herein;

[0013] FIG. 2 schematically depicts another fiber array unit according to one or more embodiments shown and described herein;

[0014] FIG. 3 depicts a plot of v-groove depth as a function of non-circularity for a fiber array unit having polarization maintaining fiber with the orientation depicted in FIG. 2 according to one or more embodiments shown and described herein;

[0015] FIG. 4 schematically depicts another fiber array unit according to one or more embodiments shown and described herein;

[0016] FIG. 5 schematically depicts another fiber array unit according to one or more embodiments show n and described herein; and

[0017] FIG. 6 depicts a plot of v-groove depth as a function of non-circularity for a fiber array unit having polarization maintaining fiber with the orientation depicted in FIG. 4 according to one or more embodiments shown and described herein.DETAILED DESCRIPTION

[0018] Reference will now be made in detail to various embodiments of devices, assemblies, and methods, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0019] Optical fiber cables include a bundle of fibers extending axially therethrough. A fiber array unit may be positioned at an end of the cable to arrange the optical fibers withinan array (such as a one dimensional or two dimensional array). In particular, the fiber array unit is useful in coupling light from a source array to the optical fibers and / or from the optical fibers to another component, like a set of waveguides or the like. Accordingly, positioning of fibers within the array must be very precise to avoid alignment issues which could hamper light transmission between components. Cable bundles may in some cases include a mixture of fibers (e.g.. single mode fibers and polarization maintaining fibers). As described above, such fibers may not have the same cross-sections, accordingly, conventional fiber array units may not be made to properly align both single mode fibers and polarization maintaining fibers. Embodiments of the present disclosure address such issues to provide a fiber array units with improved alignment, resulting in improved communication for mixed fiber bundles.

[0020] For example, FIG. 1 schematically depicts a fiber array unit including a substrate, a single mode fiber, and a polarization maintaining fiber. In some embodiments, the substrate may define a first v-groove having a first depth and a second v-groove having a second depth different from the first depth. The single mode fiber may be retained within the first v-groove of the substrate and may have a substantially circular cross sectional shape. The polarization maintaining fiber may be retained within the second v-groove of the substrate and may have a cross sectional shape with non-circulanty. The second depth may be selected based on the non-circularity of the cross sectional shape. By accounting for non-circularity, in some embodiments, the selection of the second depth may increase core-to-core alignment of the single mode fiber and the polarization maintaining mode fiber. This may increase performance of the fiber array unit by providing improved core to core alignment.

[0021] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation unless otherwise specified.

[0022] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any device or assembly claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an device or assembly is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds forany possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0023] As used herein, the singular forms “a,”L‘an” and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0024] Referring to FIG. 1. an embodiment of a fiber array unit 1 is schematically depicted. The fiber array unit 1 may include both a single mode fiber 10 and a polarization maintaining fiber 20 (or multiples thereof) co-packaged within a package substrate 30. As will be described in greater detail herein, the single mode fiber 10 and the polarization maintaining fiber 20 may differ in size and / or ovality.

[0025] The single mode fiber 10 and the polarization maintaining fiber 20 may be housed within a central channel 38 defined between an upper portion 36 and a lower portion 40 of the package substrate 30. More specifically, the single mode fiber 10 and the polarization maintaining fiber 20 may be retained within v-grooves 32 defined by the lower portion 40 of the package substrate 30. This may prevent movement of the single mode fiber 10 and the polarization maintaining fiber 20 within the central channel 38. As depicted the v-grooves 32 may each have a substantially V shape, creating a saw-like profile of the lower portion 40 of the package substrate 30. The substrate 30, including the lower portion 40 and the upper portion 36 may be formed of any suitable materials including, but not limited to, glass, acrylic, polymer, metal, or the like. Grooves may be formed through any suitable manufacturing process such as via machining with lasers, saws, or the like.

[0026] Methods of manufacturing the fiber array unit 1 may include machining the v- grooves 32 within the package substrate 30, aligning the single mode fiber 10 and the polarization maintaining fiber 20 within the v-grooves, and fixing the single mode fiber 10 and the polarization maintaining fiber 20 within the v-grooves 32 using an adhesive, for example, such as an optical adhesive. In embodiments, the upper portion 36 and the lower portion 40 may be separate from one another and fixed to one another via spacers, adhesives, fasteners, etc.

[0027] Referring now to FIG. 2, an embodiment of a fiber array unit 100 is schematically depicted, illustrating misalignment of adjacent fiber cores. The fiber array unit 100 is substantially similar to the fiber array unit 1 and includes like features. For example, the fiber array unit 100 may include a single mode fiber 110 and a polarization maintaining fiber 120 housed within a single package substrate 130.

[0028] As depicted, the single mode fiber 110 may include a circular core 112 surrounded by circular cladding 114. The circular cladding 114 may have a substantially circular cross sectional shape defining an outer circumference 116 which may be characterized by a radius R.

[0029] As depicted, the single mode fiber 110 may be retained within a first v-groove 132 of lower portion 140 of the package substrate 130 so as to be sandwiched between the lower portion 140 and the upper portion 136 of the package substrate 130. The first v-groove 132 may be characterized by a depth Di into the package substrate 130 and an angle 0i. As will be appreciated by those skilled in the art, the depth Di and the angle 0i control the relative depth of the single mode fiber 110 within the first v-groove 132. For example, increasing the angle 0i of the first v-groove 132 will cause the single mode fiber 110 to be retained deeper within the first v-groove 132. Similarly, increasing the depth Di of the first v-groove 132, while maintaining the angle 0i, will cause the single mode fiber 1 10 to be retained deeper within the first v-groove 132. In this way, the depth Di and the angle 0i may control the relative location of a longitudinal axis A extending through the circular core 112 of the single mode fiber 110.

[0030] Still referring to FIG. 2, the polarization maintaining fiber 120 may include a single mode core 122, a first stress rod 124a, and a second stress rod 124b surrounded by a non-circular cladding 126. The single mode core 122 may be arranged betw een the first stress rod 124a and the second stress rod 124b such that the single mode core 122, the first stress rod 124a. and the second stress rod 124b are aligned along a minor axis X (also referred to as a slow polarization axis). The non-circular cladding 126 may define an outer perimeter 128 having a substantially elliptical cross sectional shape, wherein the outer perimeter 128 is narrowest at the minor axis X and longest at a major axis Y (also referred to as the fast polarization axis) orthogonal to the minor axis X. The elliptical cross sectional shape may be formed during manufacturing of the polarization maintaining fiber 120 as a result of the difference in material composition of the polarization maintaining fiber 120 between the major axis Y and the minor axis X, i.e. the inclusion of the first stress rod 124a and the second stressrod 124b along the minor axis X, when the polarization maintaining fiber 120 is drawn. The elliptical shape, or non-circularity, of the outer perimeter 128 of the polarization maintaining fiber 120 is defined according to the following equation:

[0031] Non — circularity

[0032] where DY is the radius of the polarization maintaining fiber 120 along the major axis Y and Dx is the radius of the polarization maintaining fiber 120 along the minor axis X.

[0033] In some embodiments, the radius Dx may not be known. Instead, only the radius DY may be known. In such an embodiment, the non-circularity may be measured, and the radius Dx may be calculated according to Equation (1), above.

[0034] As depicted, the polarization maintaining fiber 120 may be retained between a second v-groove 134 and the upper portion 136 of the package substrate 130. In particular, in some embodiments, the polarization maintaining fiber 120 may be arranged such that the minor axis X is substantially aligned with the horizontal direction. In other words, the minor axis X may be substantially parallel with the upper portion 136 of the package substrate 130.

[0035] Still referring to FIG. 2, in some embodiments, the polarization maintaining fiber 120 may be sized such that the polarization maintaining fiber 120 does not contact both the upper portion 136 and the second v-groove 134. In such embodiments, the polarization maintaining fiber 120 may float between the upper portion 136 and the second v-groove 134. This may provide an unreliable orientation of the polarization maintaining fiber 120.

[0036] The second v-groove 134 may be characterized by a depth D2 into the package substrate 130 and an angle O2 and a horizontal span D4. As will be appreciated by those skilled in the art, the depth D2 and the angle 02 control the relative depth of the polarization maintaining fiber 120 within the first v-groove 132. Accordingly, the depth D2 and the angle 02 may control a relative distance D3 between the single mode core 122 and the longitudinal axis A extending through the circular core 112 of the single mode fiber 110. For example, as depicted, the depth D2 and the angle 02 of the second v-groove 134 cause the single mode core 122 to be positioned beneath the longitudinal axis A at the relative distance Ds. Increasing the depth D2, increasing the angle 02, or both will cause the polarization maintaining fiber 120 to be positioned deeper within the second v-groove 134, thereby increasing the relative distance D3 between the singlemode core 122 and the longitudinal axis A. In contrast, decreasing the depth D2. decreasing the angle 02, or both will cause the polarization maintaining fiber 120 to be positioned higher, thereby decreasing the relative depth D3 of the single mode core 122.

[0037] As will be appreciated by those skilled in the art, performance of the fiber arrayunit 100 may be improved when the core-to-core alignment is improved, i.e. when the relative distance D3 between the single mode core 122 and the longitudinal axis A extending through the circular core 112 of the single mode fiber 110 is minimized. Accordingly, in some embodiments, it may be beneficial to adjust the size and shape of the second v-groove 134 relative to the first v-groove. For example, as depicted in FIG. 2, it may be beneficial in some embodiments to decrease the angle 02 of the second v-groove 134 relative to the angle 0i of the first groove and / or decrease the depth D2 of the second v-groove 134 the depth Di of the first v-groove 132. In other words, in some embodiments the depth D2 may be less than the depth Di. Similarly, in some embodiments, the angle 02 may be smaller than the angle 0i. This may effectively raise the polarization maintaining fiber 120, thereby decreasing the relative distance D3 between the single mode core 122 and the longitudinal axis A extending through the circular core 112 of the single mode fiber 110. In this way, the core-to-core alignment may be improved, thereby improving the performance of the fiber array unit 100. In some embodiments, the single mode core 122 and the circular core 112 may be horizontally aligned, such as depicted in FIG. 1 and 4. In other words the relative distance D3 may be 0.

[0038] Referring now to FIG. 3, FIG. 3 depicts the relationship between the noncircularity of the polarization maintaining fiber 120 and the difference in v-groove depth (i.e. D1-D2) for embodiments in which D3=0. The data depicted in FIG. 3 illustrates a horizontally aligned major axis Y (such as depicted in FIG. 2) and fixed sizing of the first v-groove 132 and the single mode fiber 110.

[0039] As depicted, to maintain D3=0, i.e. horizontal alignment of the single mode core 122 and the circular core 1 12, the difference in v-groove depth may be increased for greater magnitudes of non-circularity. In other words, the depth D2 may be shallower in comparison to the depth Di for a more oblong polarization maintaining fiber 120.

[0040] Accordingly, in light of FIGS. 2 and 3, in some embodiments, the angle 02 and / or the depth D2 of the second v-groove 134 may be selected based on the non-circularity of the outer perimeter 128 of the polarization maintaining fiber 120. More specifically, theangle 02 and / or the depth D2 of the second v-groove 134 may be selected such that the relative distance Ds is 0, such as depicted in FIG. 1 of 4. In other words, the single mode core 122 and the circular core 112 may be horizontally aligned. Accordingly, by minimizing the relative distance Ds, the performance of the fiber array unit 100 may be improved.

[0041] In some embodiments, the relative distance Ds may approach 0 when the following equation is satisfied:

[0043] where k is the slope of the second v-groove 134 based on the angle 92, i.e. D4 / D2. Accordingly, in some embodiments, the angle 02 and the depth D2 of the second v-groove 134 may be selected to satisfy Equation (2).

[0044] This is shown, for example, in FIG. 4. FIG. 4 depicts an embodiment of a fiber array unit 100’. The fiber array unit 100’ is substantially similar to the fiber array units 1 and 100. Accordingly, like numbers are used to refer to like features. As depicted, the angle 62 and the depth D2 of the second v-groove 134 satisfy Equation (2), and the single mode core 122 and the circular core 112 are horizontally aligned. Accordingly, there is no (or negligible) relative distance D3. Additionally, as shown, the polarization maintaining fiber 120 may contact both the second v-groove 134 and the upper portion 136 when the angle 02 and the depth D2 of the second v-groove 134 satisfy Equation (2).

[0045] In light of FIGS. 2-4, a method of manufacturing the fiber array unit 100 may include selecting sizing of the first v-groove 132 and the second v-groove 134. More specifically, the method may include selecting the angle 02 and / or the depth D2 of the second v-groove 134 based, at least in part, on the non-circularity of the outer perimeter 128 of the polarization maintaining fiber 120, whereas the first groove angle 0i and / or the depth Di may be selected via conventional means. The method may include machining the first v-groove 132 and the second v-groove 134 within the package substrate 130 to the selected sizing for each groove. The method may then include aligning the single mode fiber 110 within the first v- groove 132 and aligning the polarization maintaining fiber 120 within the second v-groove 134. The method may include fixing the single mode fiber 110 and the polarization maintaining fiber 120 within the package substrate 130 using an adhesive, such as an optical adhesive. Accordingly, the single mode fiber 110 may be positioned within the first v-groove 132, andthe polarization maintaining fiber 120 may be positioned within the second v-groove 134 as depicted, for example, in FIG. 1. It is noted while only alignment and position of two fibers within two grooves are described, the method may be applied to any number of fibers and grooves within a package substrate.

[0046] Referring now to FIG. 5, an embodiment of a fiber array unit 200 is schematically depicted, showing misalignment of adjacent cores. The fiber array unit 200 is substantially similar to the fiber array units 1 and 100. Accordingly, like number will be used to refer to like features. For example, the fiber array unit 100 may include a single mode fiber 110 and a polarization maintaining fiber 120 housed within a package substrate 130.

[0047] As depicted, the polarization maintaining fiber 120 may be retained between the second v-groove 134 and the upper portion 136 of the package substrate 130. In particular, the polarization maintaining fiber 120 may be arranged such that the major axis Y is substantially aligned with the horizontal direction. In other words, the major axis Y may be substantially parallel with the upper portion 136 of the package substrate 130, while the minor axis X may be substantially orthogonal to the upper portion 136. The elliptical shape, or non-circularity, of the outer perimeter 128 of the polarization maintaining fiber 120 can be described according to Equation 1.

[0048] Similar to the embodiment described with reference to FIG. 2, as depicted in FIG. 5, the depth D2 and the angle O2 of the second v-groove 134 may control the relative depth of the polarization maintaining fiber 120 within the first v-groove 132. Accordingly, the depth D2 and the angle 02 may control the relative distance D3 between the single mode core 122 and the longitudinal axis A extending through the circular core 112 of the single mode fiber 110.

[0049] Referring now to FIG. 6, FIG. 6 depicts the relationship between the noncircularity of the polarization maintaining fiber 120 and the difference in v-groove depth (i.e. D1-D2) for embodiments in which Ds=0. The data depicted in FIG. 5 assumes a vertically aligned minor axis X (such as depicted in FIG. 4) and fixed sizing of the first v-groove 132 and the single mode fiber 110.

[0050] As depicted, to maintain Ds=0, i.e. horizontal alignment of the single mode core 122 and the circular core 112, the difference in v-groove depth may be increased in terms of magnitude for greater magnitudes of non-circularity. In other words, the depth D2 may be deeper in comparison to the depth Di for a more oblong polarization maintaining fiber 120.

[0051] Accordingly, in light of FIGS. 5 and 6, in some embodiments, the angle 02 and / or the depth D2 of the second v-groove 134 may be selected based on the non-circularity of the outer perimeter 128 of the polarization maintaining fiber 120. In some embodiments, the angle 02 and / or the depth D2 of the second v-groove 134 may be selected based on the orientation of the minor axis X of the polarization maintaining fiber 120. By selecting the sizing based on non-circularity of the outer perimeter 128 and / or the orientation of the minor axis X, the relative distance D3 may be decreased. In particular, in some embodiments, the angle 02 and / or the depth D2 of the second v-groove 134 may be selected such that the relative distance D3 is 0. In some embodiments, by minimizing the relative distance D3, the performance of the fiber array unit 200 may be improved.

[0052] Embodiments of the present disclosure are further described with respect to the following numbered clauses:

[0053] 1. A fiber array unit comprising: a substrate defining a first v-groove having a first depth and a second v-groove having a second depth different from the first depth; a single mode fiber retained within the first v-groove of the substrate, the single mode fiber having a substantially circular cross sectional shape; and a polarization maintaining fiber retained within the second v-groove of the substrate, the polarization maintaining fiber having a cross sectional shape with non-circularity. wherein the second depth is selected based on the non-circularity of the cross sectional shape.

[0054] 2. The fiber array unit of clause 1. wherein the single mode fiber has a circular core and the polarization maintaining fiber has a single mode core, wherein the circular core and the single mode core are horizontally aligned.

[0055] 3. The fiber array unit of any preceding clause, wherein the first depth is greater than the second depth.

[0056] 4. The fiber array unit of any preceding clause, wherein the second v- groove defines a groove angle, wherein the groove angle is selected based on the non- circularity of the cross sectional shape of the polarization maintaining fiber.

[0057] 5. The fiber array unit of any preceding clause, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a vertically aligned major axis.

[0058] 6. The fiber array unit of any preceding clause, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis radius and a minor axis radius, and wherein a slope of the second v-groove is substantially defined by

[0060] where k is the slope, Dx is the minor axis radius, DY is the major axis radius, and D is a horizontal span of the second v-groove.

[0061] 7. A method of manufacturing a fiber array unit comprising: machining a first v-groove of a substrate having a first depth; machining a second v-groove of the substrate having a second depth different from the first depth; aligning a single mode fiber within the first v-groove; and aligning a polarization maintaining fiber within the second v-groove, the polarization maintaining fiber having a non-circularity. wherein the machining the second v- groove comprises selecting the second depth based on the non-circularity of the polarization maintaining fiber.

[0062] 8. The method of clause 7 further comprising fixing the single mode fiber and the polarization maintaining fiber with an adhesive.

[0063] 9. The method of any of clauses 7-8, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a vertically aligned minor axis.

[0064] 10. The method of any of clauses 7-9, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a minor axis with an alignment, wherein selecting the second depth is based on the alignment of the minor axis.

[0065] 11. The method of any of clauses 7-10 wherein machining the second v- groove comprises selecting a groove angle based on the non-circularity of the polarization maintaining fiber.

[0066] 12. The method of clause 11 wherein the groove angle of the second v- groove is a second v-groove angle, wherein the second v-groove angle differs from a first v- groove angle of the first v-groove.

[0067] 13. The method of any of clauses 7-12, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis radius and a minor axis radius, and wherein a slope of the second v-groove is substantially defined by

[0069] where k is the slope, Dx is the minor axis radius, DY is the major axis radius, and D is a horizontal span of the second v-groove.

[0070] 14. A fiber array unit comprising: a substrate comprising a first v-groove having a first angle and a second v-groove having a second angle different from the first angle; a single mode fiber retained within the first v-groove of the substrate, the single mode fiber comprising a substantially circular outer perimeter and a circular core; and a polarization maintaining fiber retained within the second v-groove of the substrate, the polarization maintaining fiber comprising a cross sectional shape having non-circularity and a single mode core, wherein the second angle is selected based on the non-circularity of the polarization maintaining fiber such that the single mode core and the circular core are horizontally aligned.

[0071] 15. The fiber array unit of clause 14, wherein the first v-groove has a first depth, and the second v-groove has a second depth different from the first depth.

[0072] 16. The fiber array unit of any of clauses 14-15, wherein the first depth is greater than the second depth.

[0073] 17. The fiber array unit of any of clauses 14-17, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis and a minor axis, wherein the second angle is selected based on an alignment of the minor axis.

[0074] 18. The fiber array unit of clause 17 wherein the minor axis is horizontally aligned.

[0075] 19. The fiber array unit of any of clauses 14-18, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis radius and a minor axis radius, and wherein a slope of the second v-groove is substantially defined by

[0077] where k is the slope, Dx is the minor axis radius, DY is the major axis radius, and D is a horizontal span of the second v-groove.

[0078] 20. The fiber array unit of any of clauses 14-19, wherein the second angle is larger than the first angle.

[0079] In view of the above, it should now be understood that at least some embodiments of the present disclosure are directed to a fiber array unit including a substrate, a single mode fiber, and a polarization maintaining fiber. In some embodiments, the substrate may define a first v-groove having a first depth and a second v-groove having a second depth different from the first depth. The single mode fiber may be retained within the first v-groove of the substrate and may have a substantially circular cross sectional shape. The polarization maintaining fiber may be retained within the second v-groove of the substrate and may have a cross sectional shape with non-circularity. The second depth may be selected based on the noncircularity7of the cross sectional shape. By accounting for non-circularity, in some embodiments, the selection of the second depth may increase core-to-core alignment of the single mode fiber and the polarization maintaining mode fiber. This may increase performance of the fiber array unit.

[0080] It is noted that the terms "substantially" and "about" may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary7from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0081] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

Claims

What is claimed is:

1. A fiber array unit comprising: a substrate defining a first v-groove having a first depth and a second v-groove having a second depth different from the first depth; a single mode fiber retained within the first v-groove of the substrate, the single mode fiber having a substantially circular cross sectional shape; and a polarization maintaining fiber retained within the second v-groove of the substrate, the polarization maintaining fiber having a cross sectional shape with non-circularity. wherein the second depth is selected based on the non-circularity of the cross sectional shape.

2. The fiber array unit of claim 1, wherein the single mode fiber has a circular core and the polarization maintaining fiber has a single mode core, wherein the circular core and the single mode core are horizontally aligned.

3. The fiber array unit of claim 1, wherein the first depth is greater than the second depth.

4. The fiber array unit of claim 1 , wherein the second v-groove defines a groove angle, wherein the groove angle is selected based on the non-circularity of the cross sectional shape of the polarization maintaining fiber.

5. The fiber array unit of claim 1, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a vertically aligned major axis.

6. The fiber array unit of claim 1, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis radius and a minor axis radius, and wherein a slope of the second v-groove is substantially defined bywhere k is the slope, Dx is the minor axis radius. DY is the major axis radius, and D is a horizontal span of the second v-groove.

7. A method of manufacturing a fiber array unit comprising:machining a first v-groove of a substrate having a first depth; machining a second v-groove of the substrate having a second depth different from the first depth; aligning a single mode fiber within the first v-groove; and aligning a polarization maintaining fiber within the second v-groove, the polarization maintaining fiber having a non-circularity wherein the machining the second v-groove comprises selecting the second depth based on the non-circularity of the polarization maintaining fiber.

8. The method of claim 7 further comprising fixing the single mode fiber and the polarization maintaining fiber with an adhesive.

9. The method of claim 7 wherein the polarization maintaining fiber has an elliptical cross sectional shape having a vertically aligned minor axis.

10. The method of claim 7, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a minor axis with an alignment, wherein selecting the second depth is based on the alignment of the minor axis.

11. The method of claim 7 wherein machining the second v-groove comprises selecting a groove angle based on the non-circularity of the polarization maintaining fiber.

12. The method of claim 11 wherein the groove angle of the second v-groove is a second v-groove angle, wherein the second v-groove angle differs from a first v-groove angle of the first v-groove.

13. The method of claim 7, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis radius and a minor axis radius, and wherein a slope of the second v-groove is substantially defined bywhere k is the slope, Dx is the minor axis radius. DY is the major axis radius, and D is a horizontal span of the second v-groove.

14. A fiber array unit comprising: a substrate comprising a first v-groove having a first angle and a second v-groove having a second angle different from the first angle; a single mode fiber retained within the first v-groove of the substrate, the single mode fiber comprising a substantially circular outer perimeter and a circular core; and a polarization maintaining fiber retained within the second v-groove of the substrate, the polarization maintaining fiber comprising a cross sectional shape having non-circularity and a single mode core, wherein the second angle is selected based on the non-circularity of the polarization maintaining fiber such that the single mode core and the circular core are horizontally aligned.

15. The fiber array unit of claim 14, wherein the first v-groove has a first depth, and the second v-groove has a second depth different from the first depth.

16. The fiber array unit of claim 15, wherein the first depth is greater than the second depth.

17. The fiber array unit of claim 14, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis and a minor axis, wherein the second angle is selected based on an alignment of the minor axis.

18. The fiber array unit of claim 17 wherein the minor axis is horizontally aligned.

19. The fiber array unit of claim 14, wherein the polarization maintaining fiber has an elliptical cross sectional shape having a major axis radius and a minor axis radius, and wherein a slope of the second v-groove is substantially defined bywhere k is the slope, Dx is the minor axis radius. DY is the major axis radius, and D is a horizontal span of the second v-groove.

20. The fiber array unit of claim 14, wherein the second angle is larger than the first angle.

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