2D collimator array with reduced back reflection

Abstract

The present disclosure provides a 2D collimator array with reduced back reflection. In particular, the present disclosure describes a system and method for providing a 2D collimator array with reduced back reflection. The collimator array includes a pair of angled glass plates disposed between the lens array and the fiber array. The lens array and the fiber array each include a plurality of angled apertures.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to U.S. Provisional Patent Application No. 63 / 706,102, filed October 11, 2024, entitled “2D Collimator ARRAY WITH REDUCED BACK REFLECTION,” the entire contents of which are incorporated herein by reference. Background Technology

[0003] By comparing some aspects of the present method and system as illustrated in the remainder of this disclosure with reference to the accompanying drawings, the limitations and disadvantages of conventional collimator arrays will become apparent to those skilled in the art. Summary of the Invention

[0004] The system and method provide a 2D collimator array with reduced back reflection, substantially as shown in at least one of the figures in the accompanying drawings and / or described in conjunction with at least one of the figures in the accompanying drawings, as set forth more fully in the claims. Attached Figure Description

[0005] Figure 1 Example structures of 2D collimator arrays with lens arrays and fiber arrays having angled apertures are shown according to various exemplary implementations of this disclosure.

[0006] Figure 2 Example matrix grids of fiber arrays and lens arrays according to various exemplary implementations of this disclosure are shown.

[0007] Figure 3A , Figure 3B and Figure 3C An example 2D collimator array is shown according to various exemplary implementations of the present disclosure, the 2D collimator array comprising a flat fiber array and a flat lens array.

[0008] Figure 4A , Figure 4B and Figure 4C An example of an uncompensated 2D collimator array according to various exemplary implementations of this disclosure is shown, the 2D collimator array comprising an angled fiber array and an angled lens array.

[0009] Figure 5A , Figure 5B and Figure 5C An example 2D collimator array with compensation is shown according to various exemplary implementations of the present disclosure. The 2D collimator array includes an angled fiber array and an angled lens array.

[0010] Figure 6 An example ray tracing comparison of three collimator arrays according to various example implementations of this disclosure is shown. Detailed Implementation

[0011] The accompanying drawings illustrate the general construction method. To avoid unnecessarily obscuring this disclosure, descriptions and details of well-known features and techniques may be omitted. Furthermore, the elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding the examples discussed in this disclosure. The same reference numerals in different drawings denote the same elements.

[0012] The term "and / or" refers to any one or more items in a list connected by "and / or". As an example, "x and / or y" refers to any element in the three-element set {(x), (y), (x, y)}. In other words, "x and / or y" means "one or both of x and y". As another example, "x, y and / or z" refers to any element in the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" means "one or more of x, y, and z".

[0013] The terms “comprises”, “comprising”, “includes” and / or “including” are “open-ended” terms and specify the presence of the stated feature, but do not exclude the presence or addition of one or more other features.

[0014] The terms “first,” “second,” etc., may be used herein to describe various elements, and these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, a first element discussed in this disclosure may be referred to as a second element without departing from the teachings of this disclosure.

[0015] Unless otherwise specified, the term "coupled" can be used to describe two elements that are in direct contact with each other or to describe two elements that are indirectly connected through one or more other elements. For example, if element A is coupled to element B, then element A can be in direct contact with element B or indirectly connected to element B through an intermediary element C. Similarly, the terms "above" or "on top of" can be used to describe two elements that are in direct contact with each other or to describe two elements that are indirectly connected through one or more other elements.

[0016] Furthermore, any numerical ranges listed herein are intended to include all subranges covered therein. For example, the range “1 to 10” is intended to include any and all subranges between the listed minimum value 1 and the listed maximum value 10, including both the listed minimum and maximum values; that is, all subranges that begin with a minimum value equal to or greater than 1 and end with a maximum value equal to or less than 10, and all subranges in between, such as 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1.

[0017] For a single collimator or a 1D collimator array, the fiber end face can be angled relative to the lens surface to reduce back reflections. However, this method is not feasible for 2D arrays because the surfaces of the fiber array and the lens array must be parallel to achieve proper alignment.

[0018] Figure 1 An example structure of a 2D collimator array having a lens array 109 and an fiber array 115 according to various exemplary implementations of the present disclosure is shown. The lens array 109 and the fiber array 115 each include a plurality of angled apertures.

[0019] Fiber optic array 115 includes fiber optic cable 101 and fiber optic substrate 103. Fiber optic substrate 103 includes apertures that allow fiber optic cable 101 to pass through. The centers of the apertures in fiber optic substrate 103 are aligned with a designed matrix grid, an example of which is shown in [example of the designed matrix grid]. Figure 2 As shown in the diagram, there is an angle (θ) between the central axis of the through-hole and the surface normal axis of the fiber substrate 103. The angle (θ) is configured to reduce reflections coupled back from the fiber end to the fiber core.

[0020] Optical fiber 101 is configured with propagation modes. A single mode allows the beam to propagate with low loss within the core of optical fiber 101. Each optical fiber 101 can pass through a separate aperture and can be bonded to the aperture with epoxy resin. The ends of optical fibers 101 can be polished together with the surface of substrate 103. The beam emitted from the ends of optical fibers 101 can be diverse.

[0021] The flat glass plate 107 can be designed to have a certain thickness and may include an anti-reflective (AR) coating 111 on its first side to prevent reflective coupling back to the fiber core. The flat glass plate 107 may have a refractive index very close to that of the fiber core 101. The first side of the flat glass plate 107 may be coated with AR 111 to reduce reflections in the operating wavelength range.

[0022] The second side of the flat glass plate 107, which does not have the AR (Advanced Refractive Index), can be bonded to the fiber array 115 with epoxy resin 105, which can have a refractive index close to that of the fiber core 101 and the glass plate 107. The thickness of the glass plate 107 can be configured to further reduce reflections coupled back from the AR 111 surface to the fiber core.

[0023] Lens array 109 can be configured and positioned to provide a collimated beam. Each lens in lens array 109 can be identical and have the same focal length φ. The refractive index of lens array 109 can be selected to be as large as possible to achieve a relatively flat lens curvature for a given focal length. The focal length can be configured according to the desired characteristics of the output collimated beam, such as the beam waist and working distance.

[0024] The lens array 109 can be placed at a certain distance from the fiber array 115 and parallel to the fiber array. This distance can be configured according to collimation requirements. The center of each lens is aligned with the center of the beam from the core of the corresponding fiber 101 in the fiber array 115.

[0025] If the beam originates from an angled end of the fiber 101 core without compensation, the beam's principal axis may not be perpendicular to the corresponding lens in the lens array 109. This could introduce significant distortion into the beam after it passes through the lens array 109. To compensate for this distortion, angled glass plates 113A and 113B are introduced.

[0026] The chamfer angle (α) can be configured based on the distortion caused by the fiber end angle (α) and the lens curvature. This prevents back reflections from being coupled into the fiber 101 core.

[0027] Angled glass plates 113A and 113B each have the same chamfer angle (𝛼) and thickness. For example... Figure 1 As shown, the angled glass plates 113A and 113B are positioned such that the thicker side of the angled glass plate 113A is close to the thinner side of the angled glass plate 113B, and the thicker side of the angled glass plate 113B is close to the thinner side of the angled glass plate 113A. The angled glass plates 113A and 113B each have the same refractive index as the lens array 109.

[0028] The angled glass plates 113A and 113B can be referred to as a pair of wedges. Besides compensating for distortion, the angled glass plates 113A and 113B also ensure that all lenses remain focused on the fiber tip. Furthermore, the angled glass plates 113A and 113B can be used to finely adjust the optical length between the fiber tip and the lens element by sliding each of them in opposite directions.

[0029] This disclosure employs an angled end face of the fiber array 115 while keeping the surface of the lens array 109 parallel to this angled end face. While this reduces back reflection, the angle can introduce beam distortion and additional insertion loss. To address this issue, a pair of glass wedges are introduced between the fiber array 115 and the lens array 109. This arrangement reduces beam distortion and enhances coupling efficiency. Back reflection of -45 dB or less can be achieved with minimal impact on insertion loss.

[0030] Figure 2 Various example implementations of this disclosure are shown for use Figure 1 Example matrix grid of fiber array 115 and lens array 109.

[0031] Fiber optic arrays and lens arrays can have the same matrix grid, with identical spacing Px and Py in the x and y dimensions, respectively. The aperture centers of the fiber optic array and lens array can be aligned with... Figure 2 The design of the matrix grid matching.

[0032] Figure 3A An example 2D collimator array according to various exemplary implementations of the present disclosure is shown, the 2D collimator array comprising a flat fiber array 115 and a flat lens array 109. Figure 3B An enlarged view of the interface between the optical fiber 101 and the lenses in the lens array 109 is shown. Figure 3C Ray tracing at the coupling side is shown. The dashed arrows correspond to example stray beams / rays. A comparison with stray beam reduction achieved via the disclosed design is provided below. Figure 6 Please provide an explanation.

[0033] A flat fiber end with refractive index-matched epoxy 105 can result in return loss of up to -38 dB.

[0034] Figure 4A An example of an uncompensated 2D collimator array according to various exemplary implementations of this disclosure is shown, the 2D collimator array comprising an angled fiber array and an angled lens array. Figure 4B An enlarged view of the interface between the optical fiber 101 and the lenses in the lens array 109 is shown. Figure 4C Ray tracing at the coupling side is shown. The dashed arrows correspond to example stray beams / rays. A comparison with stray beam reduction achieved via the disclosed design is provided below. Figure 6 Please provide an explanation.

[0035] When set at an angle (e.g., >4°), the angled fiber end with epoxy resin 105 of refractive index matching can improve return loss (e.g., <-45 dB).

[0036] However, this angle (e.g., >4°) may cause the beam to pass through the lens array 109 at a large angle, resulting in collimated beam distortion and additional insertion loss in the coupling of the paired collimator arrays.

[0037] Figure 5A An example 2D collimator array with compensation is shown according to various exemplary implementations of the present disclosure. The 2D collimator array includes an angled fiber array and an angled lens array. Figure 5B An enlarged view of the interface between the optical fiber 101 and the lenses in the lens array 109 is shown. Figure 5C Ray tracing at the coupling side is shown. The dashed arrows correspond to example beams / rays in the disclosed design.

[0038] Figure 5A , Figure 5B and Figure 5C The example 2D collimator array in the example is similar to the one described above. Figure 1 The 2D collimator array described.

[0039] Figure 6 Various example implementations according to this disclosure are shown. Figure 3A , Figure 4A and Figure 5A Example ray tracing comparison of three collimator arrays. Figure 6 Ray tracing comparison Figure 3C , Figure 4C and Figure 5C They are placed side by side to show a relative improvement in coupling efficiency.

[0040] The disclosed 2D collimator array comprises a grid of optical fibers and lenses. The fiber grid is operatively coupled to a fiber plate with angled apertures, so that light leaving the fiber is not directly reflected back into the fiber core. This helps reduce reflection. However, the angled apertures also cause the beam to bend and result in distortion.

[0041] To address this issue, the design incorporates two glass wedges between the fiber optic plate and the lens plate. These wedges counteract beam distortion, maintain lens focus, and can be adjusted to fine-tune the optical path length. This results in lower back reflection (better than −45 dB) and minimal additional loss, superior to conventional 2D collimator designs.

[0042] This 2D collimator array system includes an fiber array, a lens array, and a pair of angled glass plates. The fiber array includes multiple apertures. Each aperture is configured to receive fiber, and each aperture is angled relative to the normal of the fiber array to reduce back reflection. The lens array is positioned parallel to the fiber array and includes multiple lenses aligned with the apertures. The pair of angled glass plates is disposed between the fiber array and the lens array, and the angled glass plates are configured to compensate for beam distortion caused by the apertures in the fiber array.

[0043] In some embodiments, the angled glass plates comprise a pair of wedges having equal chamfer angles and thicknesses. In some embodiments, the pair of wedges are arranged with opposite orientations to each other.

[0044] In some embodiments, the fiber array includes a fiber substrate with through-holes. In some embodiments, the through-holes are bonded to the fiber using a refractive index-matched epoxy resin.

[0045] In some embodiments, at least one glass plate includes an anti-reflective coating. In some embodiments, the angled glass plates are slidable relative to each other to finely adjust the optical path length. In some embodiments, the 2D collimator array system provides back reflection of less than −45 dB.

[0046] In some implementations, the lens array includes a refractive index selected to flatten the curvature of the lens for a given focal length.

[0047] The disclosed method for reducing back reflections in a 2D collimator array includes: providing an array of optical fibers with angled apertures to reduce reflections returning to the fiber core, aligning a lens array parallel to the optical fiber array, placing a pair of angled glass wedges between the optical fiber array and the lens array, and using the pair of angled glass wedges to compensate for beam distortion introduced by the angled ends of the optical fibers.

[0048] In some embodiments of the method, the angled glass plates comprise a pair of wedges having equal chamfer angles and thicknesses. In some embodiments of the method, the pair of wedges are arranged with opposite orientations to each other.

[0049] In some embodiments of this method, the fiber array includes a fiber substrate with through-holes. In some embodiments of this method, the through-holes are bonded to the fiber using a refractive index-matched epoxy resin.

[0050] In some embodiments of the method, at least one glass plate includes an anti-reflective coating. In some embodiments of the method, the angled glass plates are slidable relative to each other to finely adjust the optical path length. In some embodiments of the method, the 2D collimator array system provides back reflection of less than -45 dB.

[0051] In some embodiments of the method, the lens array includes a refractive index selected to flatten the curvature of the lens for a given focal length.

[0052] While this method and / or system has been described with reference to certain implementations, those skilled in the art will understand that various changes and equivalents can be made without departing from the scope of this method and / or system. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of this disclosure without departing from its scope. Therefore, this method and / or system is not intended to be limited to the disclosed implementations, but rather to include all implementations falling within the scope of the appended claims.

Claims

1. A 2D collimator array system, comprising: An optical fiber array includes a plurality of apertures, wherein each of the plurality of apertures is configured to receive an optical fiber and is angled relative to the normal of the optical fiber array to reduce back reflections. A lens array, positioned parallel to the fiber array, wherein the lens array includes a plurality of lenses aligned with the plurality of apertures; and A pair of angled glass plates are disposed between the fiber array and the lens array, wherein the angled glass plates are configured to compensate for beam distortion caused by the plurality of apertures in the fiber array.

2. The system according to claim 1, wherein: The pair of angled glass plates include a pair of wedge-shaped members with equal chamfer angles and thicknesses, and The pair of wedges are arranged in opposite orientations.

3. The system according to claim 1, wherein: The fiber array includes a fiber substrate with through holes, and The via is bonded to the optical fiber using epoxy resin with a matching refractive index.

4. The system according to claim 1, wherein, At least one glass panel includes an anti-reflective coating.

5. The system according to claim 1, wherein, The pair of angled glass plates can slide relative to each other to finely adjust the optical path length.

6. The system according to claim 1, wherein, The system provides back reflection of less than -45 dB.

7. The system according to claim 1, wherein, The lens array includes a refractive index selected to flatten the curvature of the lens for a given focal length.

8. A method for reducing back reflections in a 2D collimator array, comprising: Provide an array of optical fibers with angled apertures to reduce reflections returning to the fiber core; Align the lens array with the fiber array in parallel; A pair of angled glass wedges are disposed between the fiber array and the lens array; as well as The pair of angled glass elements are used to compensate for beam distortion introduced by the angled ends of the optical fibers.

9. The method according to claim 8, wherein: Each angled glass wedge includes a chamfer angle and a thickness equal to the chamfer angle and thickness of another angled glass wedge. The pair of angled glass wedges are arranged in opposite orientations.

10. The method according to claim 8, wherein: The fiber array includes a fiber substrate with through holes, and The via is bonded to the optical fiber using epoxy resin with a matching refractive index.

11. The method according to claim 8, wherein, At least one glass panel includes an anti-reflective coating.

12. The method according to claim 8, wherein, The pair of angled glass wedges can slide relative to each other to finely adjust the optical path length.

13. The method according to claim 8, wherein, The system provides back reflection of less than -45 dB.

14. The method according to claim 8, wherein, The lens array includes a refractive index selected to flatten the curvature of the lens for a given focal length.

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