Side surface emitting laser pumping optical fiber side surface hot melting embedded double-clad optical fiber coupler

Abstract

The invention discloses a side emitting laser pumped fiber coupler. The output sides of a set of pump fibers are cut and polished into bevels such that pump light is emitted from the sides of the fibers by total internal reflection. A femtosecond laser is used to engrave a group of round holes on the same circumference of the double-clad fiber. And the diameter of the hole is slightly greater than that of the pumping optical fiber. And the pumping optical fiber is inserted into the circular hole of the double-clad optical fiber and is symmetrically distributed in the shape of an umbrella rib. High temperature is used to splice the pump fiber and the double-clad fiber, and all of the pump light may enter the inner layer of the double-clad fiber and travel forward along the core of the double-clad fiber.

Description

Technical Field

[0001] Embodiments disclosed herein are in the field of optical fiber devices used in optical fiber systems and methods for making optical fiber devices. More specifically, embodiments disclosed herein relate to optical fibers used in optical fiber devices, systems, and methods. Background Art

[0002] Unless otherwise indicated herein, the materials described herein are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

[0003] The coupling capacity of existing fiber optic devices is limited in terms of the total number of optical fibers that can be coupled. Therefore, it is desirable to improve the fiber optic devices of the prior art.

[0004] The subject matter claimed herein is not limited to implementations that solve any disadvantages or that operate only in environments such as described above. Rather, this background is merely provided to illustrate one example technology area in which some implementations described herein may be practiced.

[0005] These and other aspects of the invention will become more fully apparent from the following detailed description of the invention. Summary of the invention

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0007] The embodiment relates to a double-clad pump coupler made by side-fusion-melting an embedded optical fiber. The coupler includes a pump fiber and an output fiber. The pump fiber can be any kind of optical fiber. The end face of the pump fiber is processed into a specific angle. The output fiber is a double-clad fiber. The pump fiber is inserted into a hole in the side wall of the output fiber and fused by heating.

[0008] In one example, an optical coupler device includes a first optical fiber including a plurality of holes, each hole radially distributed around a core of the first optical fiber; and a plurality of second optical fibers, each second optical fiber having a first end positioned within one of the plurality of holes and a second end configured to receive an optical signal.

[0009] In another aspect of the present disclosure, in the optical coupler device, the first optical fiber includes a double-clad optical fiber, and the plurality of second optical fibers include a plurality of pump optical fibers.

[0010] In another aspect of the present disclosure, in the optical coupler device, the first end includes a multi-faceted end face having an angle causing total internal reflection of the optical signal at the multi-faceted end face.

[0011] In another aspect of the present disclosure, in the optical coupler device, the optical signal totally internally reflected at the multi-faceted end face is transmitted as a reflected optical signal within the cladding of the first optical fiber along the length direction of the first optical fiber.

[0012] In another aspect of the present disclosure, in the optical coupler device, each of the plurality of holes extends through a cladding of the first optical fiber.

[0013] In another aspect of the present disclosure, in the optical coupler device, a diameter of the plurality of holes is substantially the same as a diameter of the second optical fiber.

[0014] In another aspect of the present disclosure, in the optical coupler device, each of the plurality of second optical fibers is thermally welded to a cladding of the first optical fiber.

[0015] In another aspect of the present disclosure, in the optical coupler device, a sidewall of the hole is angled relative to a direction perpendicular to an outer surface of the first optical fiber.

[0016] In another example, an optical coupler system includes an optical coupler having: a double-clad optical fiber; and a plurality of pump optical fibers, each pump optical fiber having a first end having a multi-faceted end face disposed within a hole extending into the double-clad optical fiber, wherein the multi-faceted end face of the pump optical fiber is configured to totally internally reflect an optical signal received at a second end of the pump optical fiber as a reflected optical signal, and wherein the double-clad optical fiber is configured to transmit the reflected optical signal along a length direction within the double-clad optical fiber.

[0017] In another aspect of the present disclosure, in the optical coupler system, the hole has a sidewall that forms an angle with respect to the length direction of the double-clad optical fiber.

[0018] In another aspect of the present disclosure, in the optical coupler system, the angle of the sidewall is configured based on an angular amount of the multi-faceted end face of the pump fiber.

[0019] In another aspect of the present disclosure, in the optical coupler system, a diameter of the hole is substantially the same as a diameter of the pump fiber.

[0020] In another aspect of the present disclosure, in the optical coupler system, each of the plurality of pump fibers is bonded within the hole extending into the double-clad optical fiber.

[0021] In another aspect of the present disclosure, in the optical coupler system, the hole extending into the double-clad optical fiber extends from a core of the double-clad optical fiber through an outer cladding of the double-clad optical fiber in a radial direction.

[0022] In another example, a method of manufacturing an optical coupling device includes forming a plurality of holes in a double-clad optical fiber along a radial direction from a core of the double-clad optical fiber; and bonding one of a plurality of pump optical fibers in each of the plurality of holes.

[0023] In another aspect of the present disclosure, in the manufacturing method, one or more steps include: forming a multi-faceted end face of each of the plurality of pump fibers, the multi-faceted end face having an angle configured to provide total internal reflection at the multi-faceted end face; and inserting the multi-faceted end face into one of the plurality of holes.

[0024] In another aspect of the present disclosure, in the manufacturing method, each of the multi-faceted end faces of the plurality of pump fibers is aligned to face a length direction of the double-clad optical fiber.

[0025] In another aspect of the present disclosure, in the manufacturing method, forming the multi-faceted end face includes: inserting each of the plurality of pump fibers into one of a plurality of capillaries; and polishing the end face of the pump fiber and the face of the capillary until the end face of the pump fiber includes the multi-faceted end face having the angle configured to provide total internal reflection.

[0026] In another aspect of the present disclosure, in the manufacturing method, forming the plurality of holes includes forming the plurality of holes to have a diameter substantially the same as a diameter of the pump fiber.

[0027] In another aspect of the present disclosure, in the manufacturing method, the number of the plurality of holes is greater than two.

[0028] Additional features and advantages of the present invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practice of the present invention. The features and advantages of the present invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more apparent from the following description and the appended claims, or may be learned by practice of the present invention as set forth hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to further illustrate the above and other advantages and features of the present invention, a more specific description of the present invention will be presented with reference to the specific embodiments of the present invention shown in the accompanying drawings. It should be understood that these drawings depict only typical embodiments of the present invention and therefore should not be considered to limit the scope of the present invention. The present invention will be described and explained with additional features and details through the use of the accompanying drawings, in which:

[0030] Figure 1 is a schematic diagram illustrating an exemplary optical coupler;

[0031] FIG. 2A to FIG. 2C It is shown Figure 1 A schematic diagram of an exemplary double-clad optical fiber for an optical coupler is shown;

[0032] Figure 3 is a schematic diagram illustrating an exemplary pump fiber; and

[0033] Figure 4A and Figure 4B is shown for manufacturing Figure 3 Schematic diagram of an exemplary process for an exemplary pump fiber. DETAILED DESCRIPTION

[0034] It should be understood that the drawings and description of the present invention may have been simplified to show elements relevant to a clear understanding of the present embodiment, while other elements present in the optical lens device, the system using the optical lens device, and the method for manufacturing the optical lens device have been eliminated for clarity. One of ordinary skill in the art will recognize that other elements may be desired and / or required to implement the present embodiment. However, because such elements are well known in the art and because they do not facilitate a better understanding of the present embodiment, a discussion of such elements is not provided here. It should also be understood that the drawings included herein provide only schematic representations of currently preferred structures of the present invention, and that structures falling within the scope of the present embodiment may include structures that are different from those shown in the drawings. Reference will now be made to the drawings, in which similar structures have similar reference numerals.

[0035] As previously mentioned, existing fiber optic devices have limited coupling capabilities. Generally speaking, the total number of optical fibers that can be coupled in a fiber optic device is limited by the materials and manufacturing process.

[0036] In applications, a pump laser is used to transmit pump light (i.e., optical signal) into the inner cladding of a double-clad optical fiber through a pump coupler. Thus, the optical signal repeatedly passes through the double-clad optical fiber core by total reflection until all or most of the pump light is absorbed by the core. Here, the pump coupler is applied to high-power fiber lasers and high-power fiber amplifiers.

[0037] Figure 1is a schematic diagram showing an exemplary optical coupler. Figure 1 In the embodiment, the optical coupler 100 includes a double-clad optical fiber 200 and a pump optical fiber 300. The double-clad optical fiber 200 includes an outer cladding 210a and an inner cladding 210b disposed around a core 220. The outer cladding 210a and the inner cladding 210b include a plurality of holes h radially formed from the outside of the outer cladding 210a and extending radially inward toward the core 220. Figure 1 It can be depicted that the plurality of holes h extend through the outer cladding 210a to the inner cladding 210b, but the inner cladding 210b may be formed to have a certain diameter so that the plurality of holes h do not extend into the inner cladding 210b, or the plurality of holes h may be formed so that they extend into the inner cladding 210b but are spaced apart from the core 220. In addition, although Figure 1 It may be depicted that the diameter of the hole h is larger than the diameter of the pump fiber 300 , but in reality, the diameter of the hole h is substantially the same as the diameter of the pump fiber 300 .

[0038] In some implementations, the pump fiber 300 may be bonded to the double-clad optical fiber 200 within the hole h using an adhesive material that includes a material substantially the same as the material from which the outer cladding 210a and / or the inner cladding 210b are made. For example, the hole h may be filled with the adhesive material, and the pump fiber 300 may be inserted into the hole h. Thus, the refractive index of the pump fiber 300 and the outer cladding 210a and / or the inner cladding 210b may be substantially the same.

[0039] exist Figure 1 , the pump fiber 300 includes a cladding 310 and a core 320. The pump fiber 300 includes a multi-faceted end face 330, through which a pump signal 350 is introduced into an input end 360 of the core 320, and the pump signal 350 is substantially totally internally reflected from the multi-faceted end face 330 along a direction substantially parallel to the double-clad optical fiber 200. Here, the reflection of the pump signal 350 at the multi-faceted end face 330 is collectively referred to as a reflected pump signal 340. Therefore, the reflected pump signal 340 travels along a length direction R within the outer cladding 210a of the double-clad optical fiber 200 or within the outer cladding 210a and the inner cladding 210b. The reflected pump signal 340 traveling along the direction R does not interfere with the optical signal L traveling through the core 220 of the double-clad optical fiber 200. The direction R is generally parallel to the longitudinal axis of the core 220 and parallel to the traveling direction of the optical signal L. In some implementations, the pump signal 350 and the reflected pump signal 340 include optical signals.

[0040] FIG. 2A to FIG. 2C It is shown Figure 1 Schematic diagram of an exemplary double-clad optical fiber for an optical coupler is shown. Figure 2AIn the embodiment of the present invention, the double-clad optical fiber 200 includes a plurality of holes h radially distributed around the core 220. In some implementations, the holes h may be formed using a micro-engraving process. For example, a femtosecond laser may be used to micro-engraving holes h in the double-clad optical fiber 200. In addition, in some implementations, the sidewalls of the holes h may be smoothed before inserting the pump fiber. For example, heat may be supplied to the sidewalls of the holes h to provide a smooth surface of the sidewalls.

[0041] As discussed above, a plurality of holes h may (or may not) be formed to extend into the outer cladding 210a and the inner cladding 210b. In some implementations, the depth t1 of the holes h may be selected based on various physical aspects of the double-clad fiber 200 and the pump fiber 300. For example, the depth t1 of the holes h may be selected based on the relative sizes of the outer cladding 210a, the inner cladding 210b, and the core 220 of the double-clad fiber 200 and the relative sizes of the cladding 310 and the core 320 of the pump fiber 300. In some implementations, for a double-clad fiber 200 having a diameter Ddc of 400 μm or 600 μm, the depth t1 of the holes h may be selected to be in the range of about 180 μm to about 280 μm. For example, the depth t1 of the holes h may be selected so that the entire multi-faceted end face 330 (at Figure 1 ) is immersed (completely accommodated) in the hole h together with a specific length of the pump fiber 300 adjacent to the multi-faceted end face 330. In particular, the depth t1 of the hole h can be selected so that the core 320 of the pump fiber 300 is aligned relative to the outer cladding 210a and / or the inner cladding 210b of the double-clad optical fiber 200. In addition, the depth t1 of the hole h can be determined based on the selection of the angle β of the multi-faceted end face 330 of the pump fiber 300, as described below with respect to Figure 3 For example, when the angle β changes, the depth t1 of the hole h may also change, and the angle A relative to the normal surface of the outer cladding layer 210a may also change.

[0042] In some implementations, the depth t1 of the hole h is determined based on multiple physical and material aspects of the double-clad fiber 200 and the pump fiber 300. For example, the depth t1 of the hole h is selected so that the core 320 of the pump fiber 300 exposed at the multi-faceted end face 330 is located at a position other than the interface between the outer cladding 210a and the inner cladding 210b. The depth t1 of the hole h is selected so that the core 320 of the pump fiber 300 exposed at the multi-faceted end face 330 is located at a position other than the interface between the outer cladding 210a and the inner cladding 210b.

[0043] In addition, the depth t1 of the hole h is selected based on maintaining the structural integrity of the double-clad optical fiber 200. For example, the depth t1 of the hole h may be limited to a maximum depth corresponding to the diameter of the inner cladding 210b and the diameter of the core 220. In addition, the diameters of the double-clad optical fiber 200 and the pump optical fiber 300 are determined by the total number of pump optical fibers 300 that can be safely positioned radially around the double-clad optical fiber 200 without compromising the structural integrity of the double-clad optical fiber 200. For example, in order to maintain the structural integrity of the double-clad optical fiber 200, a minimum angular spacing between adjacent holes h should be maintained based on the diameter of the double-clad optical fiber 200 and based on the depth t1 of the hole h.

[0044] exist Figure 2A In the embodiment, the width w1 of the hole h is substantially the same as the diameter d1 of the pump fiber 300. For example, the diameter d1 of the pump fiber 300 is 125 μm, which will determine that the width w1 of the hole h is substantially 125 μm. In practice, the width w1 of the hole h will be 125 μm±1 μm to 10 μm. Of course, if an adhesive is used or a thermal welding process is performed to attach the pump fiber 300 in the hole h, the width w1 of the hole h can be increased compared to the diameter d1 of the pump fiber 300.

[0045] The hole h has a side wall that is angled relative to a direction perpendicular to the surface of the outer cladding 210a (i.e., the length direction R of the double-clad optical fiber 200). Since the multi-faceted end face 330 of the pump fiber 300 is an inclined surface, making the side wall of the hole h at an angle A relative to the normal surface of the outer cladding 210a will allow the multi-faceted end face 330 of the pump fiber 300 and a portion of the pump fiber 300 adjacent to the multi-faceted end face 330 to be accommodated in the hole h to ensure sufficient bonding of the pump fiber 300 to the double-clad optical fiber 200. Here, the angle X of the hole h may be based on the angle β of the multi-faceted end face 330 of the pump fiber 300 (in Figure 3 ) is determined to provide total reflection at the multi-faceted end face 330.

[0046] In some implementations, the longitudinal axis of the pump fiber 300 may be substantially aligned with the angle A of the hole h, such that the longitudinal axis of the pump fiber 300 may be substantially parallel to the sidewalls of the hole h. The angle A may depend on the angle β of the multi-faceted end face 330 of the pump fiber 300. For example, in order to provide alignment of the core 320 of the pump fiber 300 relative to the outer cladding 210a and / or the inner cladding 210b of the double-clad optical fiber 200, both the angle A and the angle β must be considered. Therefore, the angle A and the angle β cannot be considered to be mutually exclusive, as a change in the angle β may require a change in the angle A. Therefore, the angle β may be determined by the acceptable range of the angle A in order to achieve alignment of the core 320 of the pump fiber 300 relative to the outer cladding 210a and / or the inner cladding 210b of the double-clad optical fiber 200.

[0047] Figure 2B yes Figure 2A The double-clad optical fiber 200 is along Figure 2A The cross-sectional view of section XX. Figure 2B , the plurality of holes h1 to h10 are uniformly positioned around the circumference of the double-clad optical fiber 200. In some implementations, the total number of the plurality of holes h1 to h10 along a plane perpendicular to the length of the double-clad optical fiber 200 depends on the diameter Ddc of the double-clad optical fiber 200 and the diameter d1 of the pump optical fiber 300. For example, for a double-clad optical fiber 200 having a diameter Ddc of 600 μm (a circumference of about 1884 μm) and a pump optical fiber 300 having a diameter d1 of 125 μm, about ten holes h1 to h10 with an angular interval θ of about 36 degrees may be formed in the double-clad optical fiber 200. In addition, the depth t1 of the holes h may be in the range of about 150 μm to 200 μm. As discussed above, the plurality of holes h may (or may not) be formed to extend into the outer cladding 210a and the inner cladding 210b. Additionally, although not shown, the plurality of holes h may be formed in a spiral arrangement along the length of the double-clad optical fiber 200 in a spiral configuration, thereby accommodating an increased number of pump fibers 300 along the length of the double-clad optical fiber 200. Additionally, although not shown, the plurality of holes h may be formed in a plurality of circular configurations along the length of the double-clad optical fiber 200, each circular configuration being within its own plane perpendicular to the length of the double-clad optical fiber 200, thereby accommodating an increased number of pump fibers 300 along the length of the double-clad optical fiber 200. In the spiral configuration, one or more of the plurality of holes h may be disposed within a plane along the length of the double-clad optical fiber 200. Accordingly, each pump fiber 300 may radially extend from the double-clad optical fiber 200 in a spiral arrangement along the length of the double-clad optical fiber 200. In the plurality of circular configurations, each pump fiber 300 may radially extend from the double-clad optical fiber 200 in a plurality of rings along the length of the double-clad optical fiber 200. For example, Figure 1 , Figure 2A and Figure 2B The structure depicted in can be replicated along the length of the double-clad optical fiber 200.

[0048] exist Figure 2BIn the embodiment of the present invention, each hole h receives one of a plurality of pump fibers 300, wherein the multi-faceted end faces 330 of each pump fiber 300 are aligned to face the same direction. In some implementations, each pump fiber 300 can be heat-welded to the double-clad fiber 200 in one of the holes h1 to h10. For example, heat can be applied to the pump fiber 300 or to the pump fiber 300 and the double-clad fiber 200 so that the contact surfaces of the pump fiber 300 and the double-clad fiber 200 are welded (or fused) together. In some implementations, as discussed above, an adhesive such as a low-melting-point glass material can be used to attach the pump fiber 300 to each of the holes h1 to h10.

[0049] exist Figure 2B In the embodiment, the double-clad optical fiber 200 having holes h1 to h10 can be considered as a 1:10 optical coupler. Figure 1 The optical coupler 100 depicted in FIG. Figure 2B The configuration depicted in FIG. 1 can be considered as a multimode optical coupler, in which ten pump fibers 300 are arranged together with one double-clad fiber 200. In such a configuration, when received from the ten pump fibers 300, optical signals of multiple modes can be transmitted along the claddings 210 and 220 of the double-clad fiber 200 as reflected pump signals 340.

[0050] Figure 2C is a structure in which the diameter of the pump fiber 300 is greater than Figure 2B In another configuration of the diameter of the pump fiber 300 depicted in Figure 2A A cross-sectional view of a double-clad optical fiber 200 along XX. Figure 2C , the double-clad optical fiber 200 having holes h1 to h6 can be considered as a 1:6 optical coupler, wherein the plurality of holes h1 to h6 are evenly positioned around the circumference of the double-clad optical fiber 200. In some implementations, the total number of the plurality of holes h1 to h6 depends on the diameter Ddc of the double-clad optical fiber 200 and the diameter d1 of the pump optical fiber 300. For example, for a double-clad optical fiber 200 having a diameter Ddc of 400 μm (a circumference of about 1250 μm) and a pump optical fiber 300 having a diameter d1 of 125 μm, about six or seven holes h1 to h6 with an angular interval θ of about 60 degrees can be formed in the double-clad optical fiber 200.

[0051] In addition, in some implementations, a multimode fiber may be implemented for the pump fiber 300. For example, a 65 μm diameter multimode fiber may be used for the pump fiber 300. Thus, a 200 μm to 300 μm diameter double-clad fiber 200 may be used. Figure 2A and Figure 2B. In addition, as discussed above, the depth t1 of the hole h may be selected based on the physical parameters of the double-clad fiber 200 and the pump fiber 300, and a plurality of holes h may (or may not) be formed to extend into the outer cladding 210a and the inner cladding 210b.

[0052] Figure 3 is a schematic diagram showing an exemplary pump fiber. Figure 3 , the multi-faceted end face 330 of the pump fiber 300 includes an inclined surface that is at an angle β relative to the outer diameter Dmf of the pump fiber 300. The angle β is determined to provide substantially total internal reflection of the optical signal 360 at the multi-faceted end face 330, which is transmitted along the core 320 as a reflected pump signal 340. For an explanation of total internal reflection at an optical fiber end face, the entire disclosure of U.S. Patent No. 5,772,657 is incorporated by reference in its entirety.

[0053] As is known in the art, the angle of total internal reflection (α) and the angle of maximum propagation (θ) in an optical fiber are m ) is generally based on the refractive index n2 of the core 320 and the refractive index n1 of the medium adjacent to the core 320 at the multi-faceted end face 330, as well as the intrinsic numerical aperture (NA) of the pump fiber 330. In this regard, the angle β may be given by:

[0054] β=90-α-θ m (1)

[0055] For example, based on the various materials used to make the pump fiber 300 (such as Corning SMF-28) and the double-clad fiber 200 (such as LMA-GDF-30 / 250-M), the angle β can be in the range of about 10 degrees to about 40 degrees. In most implementations, the material of the cladding 310 of the pump fiber 300 can be substantially the same as the material of one (or both) of the outer cladding 210a and the inner cladding 210b of the double-clad fiber 200. For example, in order to reduce possible refraction of the reflected pump signal 340 at the interface between the pump fiber 300 and the adjacent surface of the double-clad fiber 200, the refractive index n2 of the core 320 of the pump fiber 300 should be substantially the same as the refractive index n1 of one (or both) of the outer cladding 210a and the inner cladding 210b of the double-clad fiber 200.

[0056] exist Figure 1In the embodiment, the pump fiber 300 is positioned in the hole h of the double-clad optical fiber 200 using a bonding method. In some implementations, as described in detail above, the pump fiber 300 may be heat-welded to the double-clad optical fiber 200 in the hole h of the double-clad optical fiber 200, or an adhesive may be used to attach the pump fiber 300 in the hole h of the double-clad optical fiber 200. Therefore, for heat welding, the angle β may depend on the refractive index n2 of the core 320 of the pump fiber 300, the refractive index n1 of one (or both) of the outer cladding 210a and the inner cladding 210b of the double-clad optical fiber 200. When an adhesive such as a low-melting point glass material is used to attach the pump fiber 300 in the hole h of the double-clad optical fiber 200, the angle β may depend on the refractive index n2 of the core 320 of the pump fiber 300, the refractive index n1 of the low-melting point glass. For example, the low-melting point glass material may include a glass from K-CaFK95, from N-FK51A and from M-FCD1.

[0057] Figure 4A and Figure 4B is shown for manufacturing Figure 3 Schematic diagram of an exemplary process for an exemplary pump fiber. Figure 4A and Figure 4B In the embodiment, the assembly 500 is used to manufacture Figure 1 The pump fiber 300 of the optical coupler 100 is depicted in FIG. Figure 4A In the embodiment of the present invention, a capillary 400 is used to accommodate the pump fiber 300 through the insertion end 420 of the capillary 400. In some implementations, the inner diameter of the capillary 400 is substantially the same as the outer diameter of the pump fiber 300. For example, the inner diameter of the capillary 400 can be slightly larger than the outer diameter of the pump fiber 300 by about 1% to 5%. The capillary 400 accommodates the pump fiber 300 in a substantially tight manner so that when the end of the pump fiber 300 is polished (such as mechanical polishing), the capillary 400 firmly holds the pump fiber 300 along the length of the pump fiber 300 residing in the capillary 400. Therefore, as shown in FIG. Figure 4A As depicted, when the end of the pump fiber 300 is polished to obtain the angle β, the outer edge of the end of the pump fiber 300 to be polished is not chipped. For example, by using the capillary 400 to support the outer edge of the end of the pump fiber 300 to be polished, the outer edge of the capillary 400 may be chipped instead of the outer edge of the end of the pump fiber 300 to be polished.

[0058] exist Figure 4A, the face 330 of the pump fiber 300 and the face 430 of the capillary 400 are substantially coplanar. Therefore, when the end of the pump fiber 300 is to be polished, portions of both the face 330 of the pump fiber 300 and the face 430 of the capillary 400 are removed simultaneously.

[0059] exist Figure 4B , once the angle β of the face 330 of the pump fiber 300 has been reached, the pump fiber 300 can be withdrawn from the insertion end 420 of the capillary. Therefore, the multi-faceted end face 330 of the pump fiber 300 is formed to have the angle β, and the outer edge of the pump fiber 300 at the multi-faceted end face 330 is not damaged, such as chipped, thereby maintaining the structural integrity of the pump fiber 300 not only at the multi-faceted end face 330 but also adjacent to the multi-faceted end face 330. Here, since the multi-faceted end face 330 and a portion of the pump fiber 300 adjacent to the multi-faceted end face 330 will be attached to the double-clad fiber 200 as discussed above, it is important to maintain the structural integrity of the pump fiber 300 at this attachment location of the pump fiber 300 to the double-clad fiber 200. Since the end of the pump fiber 300 to be polished is not supported during polishing, the attachment location of the pump fiber 300 may be damaged and prevent the pump fiber 300 from being firmly attached to the double-clad fiber 200 within the hole h.

[0060] For the double-clad optical fiber 200, the hole h can be formed by etching corresponding regions of the outer cladding layer 210a and the inner cladding layer 210b using a femtosecond laser. In addition, the etched surface of the hole h can be further treated by HF acid or heat. Then, as discussed above, the double-clad optical fiber 200 and the pump optical fiber 300 can be fused together by heating, flame heating, high-voltage arc heating, and high-temperature metal contact heating.

[0061] Unless the specific arrangements described herein are mutually exclusive, the various implementations described herein may be combined in whole or in part to enhance system functionality or generate supplementary functionality. Likewise, various aspects of the implementations may be implemented in independent arrangements. Therefore, the above description is given by way of example only, and the details may be modified within the scope of the invention.

[0062] With respect to the use of substantially any plural or singular terminology herein, those skilled in the art may appropriately interpret the plural as singular or the singular as plural, depending on the context or application. For clarity, various singular / plural arrangements may be expressly set forth herein. Unless otherwise specified, reference to an element in the singular is not intended to mean "one and only one," but rather "one or more." Furthermore, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is explicitly stated in the description above.

[0063] In general, the terms used herein and particularly in the appended claims (e.g., the body of the appended claims) are generally intended to be "open" terms (e.g., the term "including" should be interpreted as "including but not limited to", the term "having" should be interpreted as "having at least", the term "comprising" should be interpreted as "including but not limited to", etc.). In addition, in those cases where a convention similar to "at least one of A, B, and C, etc." is used, in general, such construction is intended to have the meaning that a person skilled in the art will understand the convention (e.g., "a system having at least one of A, B, and C" will include but is not limited to a system including only A, only B, only C, including A and B, including A and C, including B and C, or including A, B, and C, etc.). Similarly, whether in the specification, claims, or drawings, a statement presenting two or more alternative terms should be understood to include one of these terms, any one of these terms, or both of these terms. For example, the statement "A or B" should be understood to include the possibility of "A" or "B" or "A and B".

[0064] Without departing from the spirit or essential features of the present invention, the present invention may be embodied in other specific forms. The described embodiments should be considered in all respects as illustrative only and not restrictive. Therefore, the scope of the present invention is indicated by the appended claims rather than by the foregoing description. All changes within the equivalent meaning and scope of the claims are encompassed within their scope.

Claims

1. An optical coupler device, comprising: a first optical fiber, the first optical fiber comprising a plurality of holes, each hole being radially distributed around a core of the first optical fiber; as well as A plurality of second optical fibers each having a first end positioned within one of the plurality of holes and a second end configured to receive an optical signal.

2. The apparatus of claim 1, wherein the first optical fiber comprises a double-clad optical fiber and the plurality of second optical fibers comprises a plurality of pump fibers.

3. The apparatus of claim 1, wherein the first end comprises a multi-faceted end face having an angle that causes total internal reflection of the optical signal at the multi-faceted end face.

4. The apparatus of claim 3, wherein the optical signal totally internally reflected at the multi-faceted end face is transmitted as a reflected optical signal within the cladding of the first optical fiber along the length direction of the first optical fiber.

5. The apparatus of claim 1, wherein each of the plurality of holes extends through a cladding of the first optical fiber.

6. The apparatus of claim 1, wherein a diameter of the plurality of holes is substantially the same as a diameter of the second optical fiber.

7. The apparatus of claim 1, wherein each of the plurality of second optical fibers is thermally welded to a cladding of the first optical fiber.

8. The apparatus of claim 1, wherein a sidewall of the hole is angled relative to a direction perpendicular to an outer surface of the first optical fiber.

9. An optical coupler system, the optical coupler system comprising: An optical coupler, the optical coupler comprising: Double-clad optical fiber; and a plurality of pump fibers, each pump fiber having a first end having a multi-faceted end face disposed within a hole extending into the double-clad optical fiber, wherein the multi-faceted end face of the pump fiber is configured to totally internally reflect an optical signal received at the second end of the pump fiber as a reflected optical signal, and The double-clad optical fiber is configured to transmit the reflected optical signal along a length direction within the double-clad optical fiber.

10. The system of claim 9, wherein the hole has side walls that are angled relative to the length direction of the double-clad optical fiber.

11. The system of claim 10, wherein the angle of the sidewall is configured based on an angular amount of the multi-faceted end face of the pump fiber.

12. The system of claim 9, wherein a diameter of the hole is substantially the same as a diameter of the pump fiber.

13. The system of claim 9, wherein each of the plurality of pump fibers is bonded within the hole extending into the double-clad optical fiber.

14. The system of claim 13, wherein the hole extending into the double-clad optical fiber extends from the core of the double-clad optical fiber in a radial direction through the outer cladding of the double-clad optical fiber.

15. A method for manufacturing an optical coupling device, the method comprising: forming a plurality of holes in a double-clad optical fiber along a radial direction from a core of the double-clad optical fiber; as well as One of a plurality of pump fibers is bonded in each of the plurality of holes.

16. The method of claim 15, comprising: forming a multi-faceted end face of each of the plurality of pump fibers, the multi-faceted end face having angles configured to provide total internal reflection at the multi-faceted end face; as well as The multi-faceted end face is inserted into one of the plurality of holes.

17. The method of claim 16, wherein each of the multi-faceted end faces of the plurality of pump fibers are aligned to face a length direction of the double-clad optical fiber.

18. The method of claim 16, wherein forming the multi-faceted end face comprises: inserting each of the plurality of pump fibers into one of a plurality of capillaries; as well as The end face of the pump fiber and the face of the capillary are polished until the end face of the pump fiber includes the multi-faceted end face having the angle configured to provide total internal reflection.

19. The method of claim 15, wherein forming the plurality of holes comprises forming the plurality of holes having a diameter substantially the same as a diameter of the pump fiber.

20. The method of claim 15, wherein the number of the plurality of holes is greater than two.

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