JP-2026514376-A - Tile-shaped collimator array

Abstract

A tiled collimator array is disclosed. The tiled collimator array comprises a plurality of end caps, each connected to an optical fiber at its rear end, wherein the end caps are selected from hexagonal end caps and square end caps, and include an adhesive for bonding the end caps together, and the end caps are stacked in a compact structure. [Selection Diagram] Figure 1A

Inventors

• トゥルム，アサフ
• シュイファー，ゼーフ
• ブラチャ，リーロン ハナン
• ウォームサー，ダニエル
• コーエン，リーナ

Assignees

• エルビット システムズ エレクトロ－オプティックス－エロップ リミテッド

Dates

Publication Date

20260511

Application Date

20240326

Priority Date

20230326

Claims (12)

1. A tiled collimator array, A plurality of end caps connected to the optical fiber at the rear end, wherein the end caps are selected from hexagonal end caps and square end caps, An adhesive for bonding the end caps together, A tile-shaped collimator array comprising, The aforementioned end caps are stacked in a compact structure, forming a tile-like collimator array.
2. The tile-shaped collimator array according to claim 1, wherein the adhesive is selected from a transparent adhesive and an optical adhesive.
3. The tile-shaped collimator array according to claim 1 or 2, wherein the thickness of the adhesive is between 0.0001 and 0.1 of the diameter of the inscribed circle of the end cap cross-section.
4. The tiled collimator array according to claim 3, wherein the optical fiber is joined to the rear end such that the optical axis of the fiber merges with the optical axis of the end cap.
5. Each end cap is provided with a front lens at the second end, according to any one of claims 1 to 4.
6. The tiled collimator array according to claim 5, further comprising a diffractive optical element (DOE) located in front of the front lens on the optical axis of the tiled collimator array.
7. The tiled collimator array according to claim 5 or 6, wherein the length of the end cap is equal to or shorter than the focal length of the lens.
8. The tiled collimator array according to any one of claims 1 to 7, wherein all of the optical fibers are aligned with the same polarization.
9. The length of each end cap is determined based on the wavelength, the numerical aperture (NA) of the fiber, and the desired beam diameter, in the tiled collimator array according to any one of claims 1 to 8.
10. The tiled collimator array according to any one of claims 1 to 9, wherein the diameter of the circumscribed circle of each end cap is determined based on the desired beam diameter and the internal reflectance within the end cap.
11. The tiled collimator array according to any one of claims 1 to 10, wherein the diameter of the optical fiber core is between 5 and 50 μm.
12. The tiled collimator array according to any one of claims 1 to 11, wherein the side facets of each end cap are coated with an anti-reflective coating.

Description

This application is a PCT patent application claiming priority to Israel Patent Application No. 301657, filed on March 26, 2023. The contents of the aforementioned application are incorporated entirely by reference, as if they were fully incorporated herein in their entirety. This invention generally relates to collimator arrays. More specifically, this invention relates to tiled collimator arrays. High-power laser beams are typically achieved by combining multiple collimated, small-diameter laser beams. For effective combining, all beams must be aligned into a compact structure. This alignment must be maintained throughout the lifetime of the high-power laser, taking into account temperature changes and vibrations. In high-power laser sources, the power density within the fiber core becomes extremely high. Therefore, the exit end of the fiber (to the free-space environment) needs to be treated to avoid melting. Thus, an end cap is attached to the end of the optical fiber. The end cap is a glass block with a much larger diameter than the fiber, to which the fiber end is joined. As a result, the laser spot diameter at output is significantly increased, thereby drastically reducing the power density to a level safe for long-term laser operation. One known technique for achieving coherent beam coupling is known as tiled aperture, where multiple collimated beams are aligned to generate a desired wavefront amplitude and phase. To achieve satisfactory performance, collimators must be aligned with high precision and stability down to the micrometer level. To overcome the aforementioned drawbacks, attempts have been made to manufacture monolithic collimators by joining multiple fibers into a single glass block. One of the main drawbacks of such glass structures is that the manufacturing process is not trivial, resulting in very low yields for such products, or the possibility of damage to some fiber joints. Therefore, there is a need for a tiled collimator array for high-power lasers that minimizes retention during temperature changes and vibrations while keeping the fiber array and end caps aligned. Some aspects of the present invention relate to a plurality of end caps, each connected to an optical fiber at its rear end, wherein the end caps comprise an end cap selected from hexagonal and square end caps, and an adhesive for bonding the end caps together, and the end caps are stacked in a compact structure, and are directed toward a tiled collimator array. In some embodiments, the adhesive is selected from transparent adhesives and optical adhesives. In some embodiments, the thickness of the adhesive is between 0.0001 and 0.1 of the diameter of the inscribed circle of the end cap cross-section. In some embodiments, the optical fiber is joined to the rear end so that the optical axis of the fiber aligns with the optical axis of the end cap. In some embodiments, each end cap includes a front lens at a second end. In some embodiments, the tiled collimator array further includes a diffractive optical element (DOE) located in front of the front lens on the optical axis of the tiled collimator array. In some embodiments, the length of the end cap is equal to or shorter than the focal length of the lens. In some embodiments, all optical fibers are aligned with the same polarization. In some embodiments, the length of each end cap is determined based on the wavelength, the numerical aperture (NA) of the fiber, and the desired beam diameter. In some embodiments, the diameter of the circumscribed circle of each end cap is determined based on the desired beam diameter and the internal reflectivity within the end cap. In some embodiments, the diameter of the optical fiber core is between 5 and 50 μm. In some embodiments, the side facets of each end cap are coated with an anti-reflective coating. The main parts considered to be the present invention are specifically pointed out and explicitly asserted in the concluding section of this specification. However, the present invention, both in terms of its configuration and operation, as well as its objectives, features, and advantages, can be best understood by referring to the following detailed description when viewed together with the accompanying drawings. This is an example of a perspective view of a tiled collimator array according to some embodiments of the present invention.This is an example of a cross-sectional view of a tile-shaped collimator array according to some embodiments of the present invention.This is an example of an end cap connected to an optical fiber according to some embodiments of the present invention.This is an example of another end cap connected to an optical fiber according to some embodiments of the present invention.This is an example of reflected light returning from the lens surface to the end cap according to some embodiments of the present invention.This is an example of a perspective view of a tile-shaped collimator array equipped with hexag