Mode matching device based on space coupling

Abstract

The invention relates to a mode matching device based on space coupling. The mode matching device comprises a first optical fiber fixing piece, a packaging module and a second optical fiber fixing piece, the first optical fiber fixing piece is installed on the input side of the packaging module and used for installing a first optical fiber, adjusting input light and inputting the input light into the packaging module. The second optical fiber fixing piece is installed on the output side of the packaging module and used for installing a second optical fiber, adjusting output light of the packaging module and inputting the output light into the second optical fiber; the packaging module comprises a first dichroscope and an optical signal adjusting assembly which are sequentially arranged in the light propagation direction. The first dichroscope is used for filtering pump light in the input light; the optical signal adjusting assembly is used for adjusting the output light of the first dichroscope to meet the input requirement of the optical fiber amplifier and then outputting the light. On the basis of a space coupling mode, high-fidelity transmission of high-power and high-energy laser can be met; the structure is simple, and additional loss is not easy to introduce; the system heat influence is reduced, and the system stability is improved.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a mode matching device based on spatial coupling. Background Art

[0002] Mode field adapters are important components in the field of ultrafast fiber lasers. In order to obtain higher energy ultrashort pulse lasers, fiber lasers require cascaded multi-stage fiber amplifiers and are limited by the influence of fiber nonlinear effects (such as stimulated Raman, stimulated Brillouin, mode instability, etc.). As the laser pulse energy increases, the core diameter of the fiber amplifier must also increase gradually. Cascaded amplifiers at each level require fiber mode field adapters to achieve high-efficiency coupling and mode matching to obtain higher amplification efficiency and laser mode, and to optimize the final spectrum and pulse width.

[0003] At present, the commonly used fiber mode field adapters mostly use the fiber taper method to gradually reduce the fiber core diameter to the input signal fiber matching parameters, such as fiber core diameter and numerical aperture, so as to reduce signal transmission loss during fiber fusion and reduce mode noise, and minimize the impact of high-order mode amplification after signal coupling on the final optical pulse quality. Ultrafast laser amplifiers use optical fibers with various specifications. Passive optical fibers that are too long will increase the nonlinear phase shift during signal transmission, affecting the final ultrashort pulse laser compression quality.

[0004] In addition, the power that the fiber mode field adapter of the fiber taper method can withstand at the fusion point is relatively low. When high-energy laser amplification is performed, extremely high-power backward amplification signals may appear, including return light, stimulated Raman, spontaneous radiation, and stimulated Brillouin signals. High-energy and high-power signals can cause irreversible damage to the fusion point or mode field adapter, affecting the stability of the system. Especially when photonic crystal fiber is used for tapering, the internal air hole structure limits the preparation of its taper combiner. Tapering causes the air holes to collapse and the array arrangement to change, affecting optical parameters such as the numerical aperture and increasing the fusion loss. The above problems need to be solved urgently. Summary of the invention

[0005] The invention discloses a mode matching device based on space coupling, aiming to solve the technical problems existing in the prior art.

[0006] The present invention adopts the following technical solutions: The present invention provides a mode matching device based on spatial coupling, which comprises a first optical fiber fixing part, a packaging module and a second optical fiber fixing part; the first optical fiber fixing part is installed at the input side of the packaging module, and is used to install the first optical fiber, and adjust the input light before inputting it into the packaging module; the second optical fiber fixing part is installed at the output side of the packaging module, and is used to install the second optical fiber, and adjust the output light of the packaging module before inputting it into the second optical fiber; the packaging module comprises a first dichroic mirror and an optical signal adjustment component which are sequentially arranged along the light propagation direction; the first dichroic mirror is used to filter out the pump light in the input light; the optical signal adjustment component is used to adjust the output light of the first dichroic mirror to meet the input requirements of the optical fiber amplifier and then output it externally.

[0007] In the mode matching device based on spatial coupling of the present invention, the optical signal adjustment component includes a first half-wave plate, a Faraday rotator, a second polarization beam splitter and a second half-wave plate arranged in sequence along the light propagation direction; the first half-wave plate and the Faraday rotator are used to adjust the input light into horizontal polarized light; the second polarization beam splitter is used to transmit the horizontal polarized light in the output light of the Faraday rotator into the second half-wave plate; the second half-wave plate is used to adjust the polarization direction of the horizontal polarized light to meet the requirements of the optical fiber amplifier input and then output it.

[0008] In the mode matching device based on spatial coupling of the present invention, the optical signal adjustment component also includes a second dichroic mirror; the second dichroic mirror is arranged on the optical path between the second polarization beam splitter and the second half-wave plate, and is used to transmit the output light of the second polarization beam splitter and filter out the backward pump light.

[0009] In the mode matching device based on spatial coupling of the present invention, a signal light anti-reflection film is provided on the input light incident side of the second dichroic mirror, and a signal light high-pass film is provided on the output side; the signal light high-pass film is used to filter out the backward pump light and transmit the signal light in the input light.

[0010] In the mode matching device based on spatial coupling of the present invention, the optical signal adjustment component further includes a first polarization beam splitter; the first polarization beam splitter is arranged at the input side of the first half-wave plate and is used to filter out non-horizontally polarized light in the input light.

[0011] In the mode matching device based on spatial coupling of the present invention, the optical signal adjustment component also includes a packaging shell; the first half-wave plate, the Faraday rotator, the second polarization beam splitter and the second half-wave plate are installed inside the packaging shell, and the packaging shell is provided with a light inlet and a light outlet; the light inlet is docked and installed with the light outlet side of the first optical fiber fixing component; the light outlet is docked and installed with the light inlet side of the second optical fiber fixing component.

[0012] In the mode matching device based on spatial coupling of the present invention, a signal light high-pass film is arranged on the incident side of the input light of the first dichroic mirror for signal light transmission and pump light reflection, and a signal light anti-reflection film is arranged on the output side.

[0013] In the mode matching device based on spatial coupling of the present invention, the first optical fiber fixing part includes a first mounting seat, a concave lens and a first lens; the first mounting seat is installed on the input side of the packaging module and has a first mounting channel running through both sides; one end of the first mounting channel is used to install the end of the first optical fiber, and the other end is connected to the packaging module, and the concave lens and the first lens are arranged in sequence along the propagation direction of the input light; the concave lens is provided with a light-transmitting hole, and the signal light in the input light can be transmitted through the light-transmitting hole, and the pump light is scattered by the concave lens.

[0014] In the mode matching device based on spatial coupling of the present invention, the first mounting seat includes a first base, a first universal seat, a first elastic washer, a first bolt and a first top screw; the first elastic washer is clamped between the first base and the first universal seat; the first base is installed on the input side of the packaging module, and a first protrusion is provided on the surface facing the first universal seat; the first universal seat is connected to the first base through the first bolt, and the first universal seat is installed with the end of the first optical fiber, the concave lens and the first lens; one end of the first top screw passes through the first universal seat and abuts against the first protrusion to adjust the direction of the output end of the first optical fiber.

[0015] In the mode matching device based on spatial coupling of the present invention, the first protrusion is in tangential contact with the end of the first top wire.

[0016] In the mode matching device based on spatial coupling of the present invention, the first mounting seat also includes a first optical fiber clamp and a first fixing screw; one end of the first optical fiber clamp is located in the first mounting channel and has a first optical fiber mounting channel running through both sides; the first optical fiber mounting channel is used to detachably install the first optical fiber, and the end located in the first mounting channel has a first accommodating portion for accommodating the end cap of the first optical fiber; one end of the first fixing screw passes through the side wall of the first mounting seat and abuts against the first optical fiber clamp to fix the position of the first optical fiber clamp.

[0017] In the mode matching device based on spatial coupling of the present invention, the second optical fiber fixing part includes a second mounting seat and a second lens; the second mounting seat is installed on the input side of the packaging module and has a second mounting channel running through both sides; one end of the second mounting channel is used to mount the end of the second optical fiber, and the other end is connected to the packaging module and is provided with the second lens; the second lens is used to focus the output light of the packaging module and input it into the second optical fiber.

[0018] In the mode matching device based on spatial coupling of the present invention, the second mounting seat includes a second base, a second universal seat, a second elastic washer, a second bolt and a second top screw; the second elastic washer is clamped between the second base and the second universal seat; the second base is installed on the input side of the packaging module, and a second protrusion is provided on the surface facing the second universal seat; the second universal seat is connected to the second base through the second bolt, and the second universal seat is installed with the end of the second optical fiber and the second lens; one end of the second top screw passes through the second universal seat and abuts against the second protrusion to adjust the direction of the output end of the second optical fiber.

[0019] In the mode matching device based on spatial coupling of the present invention, the second protrusion is in tangential contact with the end of the second top wire.

[0020] In the mode matching device based on spatial coupling of the present invention, the second mounting seat also includes a second optical fiber clamp and a second fixing screw; one end of the second optical fiber clamp is located in the second mounting channel and has a second optical fiber mounting channel running through both sides; the second optical fiber mounting channel is used to detachably install the second optical fiber, and the end located in the second mounting channel has a second accommodating portion for accommodating the end cap of the second optical fiber; one end of the second fixing screw passes through the side wall of the second mounting seat and abuts against the second optical fiber clamp to fix the position of the second optical fiber clamp.

[0021] The technical solution adopted by the present invention can achieve the following beneficial effects: The present invention mainly provides a mode matching device based on spatial coupling. Based on the spatial coupling method, the nonlinear phase shift caused by the excessively long passive optical fiber is avoided, and the high-fidelity transmission of high-power and high-energy lasers can be met; the mode mismatch and energy loss caused by the traditional fusion method are avoided, the structure is simple, and additional loss is not easily introduced; the pump light is filtered out by the first dichroic mirror, the thermal impact of the system is reduced, and the system stability is improved; and photonic crystal optical fiber can be used for transmission to further improve the damage threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings: Figure 1 It is a schematic diagram of the three-dimensional structure of a mode matching device based on spatial coupling of the present invention; Figure 2 It is a schematic diagram of the main structure of a mode matching device based on spatial coupling of the present invention; Figure 3 For the present invention Figure 2 A schematic diagram of a cross-sectional structure in the ZZ direction; Figure 4 is a schematic cross-sectional structural diagram of a first optical fiber fixing member of the present invention; Figure 5 It is a schematic diagram of a three-dimensional exploded structure of a first optical fiber fixing member of the present invention; Figure 6 For the present invention Figure 2 A schematic diagram of the local enlarged structure at D; Figure 7 is a schematic cross-sectional structural diagram of a second optical fiber fixing member of the present invention; Figure 8 It is a schematic diagram of a three-dimensional exploded structure of a second optical fiber fixing member of the present invention; Fig. 9 For the present invention Figure 2 A schematic diagram of the local enlarged structure at E; Fig.10 The figure is a schematic diagram of the working structure of a mode matching device based on spatial coupling of the present invention.

[0023] Description of reference numerals: 1. First optical fiber fixing member; 11. First mounting seat; 111. First mounting channel; 112. First base; 113. First universal seat; 114. First elastic gasket; 115. First bolt; 116. First top screw; 117. First protrusion; 118. First clamp; 12. Concave lens; 121. Light transmission hole; 13. First lens; 14. First optical fiber clamp; 141. First optical fiber mounting channel; 142. First accommodating portion; 15. First fixing screw; 2. Packaging module; 21. First dichroic mirror; 22. Optical signal adjustment component; 221. First half-wave plate; 222. Faraday rotator; 223. Second polarization beam splitter; 224. Second half-wave plate; 225. Second dichroic mirror; 226. First polarization beam splitter; 227. Packaging shell; 2271. Light inlet; 2272. Light outlet; 2273. opening; 2274. cover body; 3. second optical fiber fixing member; 31. second mounting seat; 311. second mounting channel; 312. second base; 313. second universal seat; 314. second elastic gasket; 315. second bolt; 316. second top screw; 317. second protrusion; 318. second retaining ring; 32. second lens; 33. second optical fiber clamp; 331. second optical fiber mounting channel; 332. second accommodating portion; 34. second fixing screw; A. first optical fiber; B. second optical fiber; C. optical fiber amplifier; S1. pump light; S2. first non-horizontal polarized light; R1. backward pump light; R2. second non-horizontal polarized light; R3. backward harmful signal light. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and / or", unless the content clearly indicates otherwise.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a magnetic connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically limited.

[0026] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In order to solve the problems existing in the prior art, an embodiment of the present application provides a mode matching device based on spatial coupling.

[0028] like Figure 1-Figure 3 As shown, a mode matching device based on spatial coupling includes a first optical fiber fixture 1, a packaging module 2 and a second optical fiber fixture 3; the first optical fiber fixture 1 is installed on the input side of the packaging module 2, and is used to install the first optical fiber A, and adjust the input light before inputting it into the packaging module 2; the second optical fiber fixture 3 is installed on the output side of the packaging module 2, and is used to install the second optical fiber B, and adjust the output light of the packaging module 2 before inputting it into the second optical fiber B; the packaging module 2 includes a first dichroic mirror 21 and an optical signal adjustment component 22 arranged in sequence along the light propagation direction; the first dichroic mirror 21 is used to filter out the pump light S1 in the input light; the optical signal adjustment component 22 is used to adjust the output light of the first dichroic mirror 21 to meet the input requirements of the optical fiber amplifier C and then output it externally.

[0029] The present invention discloses a mode matching device based on spatial coupling. Based on the method of realizing spatial coupling by cooperating a first optical fiber fixing member 1, a packaging module 2 and a second optical fiber fixing member 3, the nonlinear phase shift caused by an excessively long passive optical fiber is avoided, and the high-fidelity transmission of high-power and high-energy lasers can be met. The mode mismatch and energy loss caused by the traditional fusion splicing method are avoided, the structure is simple, and additional losses are not easily introduced. The pump light S1 is filtered out by a first dichroic mirror, the thermal impact of the system is reduced, and the system stability is improved. Photonic crystal optical fiber can be used for transmission to further improve the damage threshold.

[0030] In some preferred embodiments, the incident side of the input light of the first dichroic mirror 21 is provided with a signal light high-pass film for signal light transmission and pump light S1 reflection, and the output side is provided with a signal light anti-reflection film.

[0031] In some preferred embodiments, Figure 3 and Fig.10As shown, the optical signal adjustment component 22 includes a first half-wave plate 221, a Faraday rotator 222, a second polarization beam splitter 223 and a second half-wave plate 224 which are arranged in sequence along the light propagation direction; the first half-wave plate 221 and the Faraday rotator 222 are used to adjust the input light into horizontal polarized light; the second polarization beam splitter 223 is used to transmit the horizontal polarized light in the output light of the Faraday rotator 222 into the second half-wave plate 224; the second half-wave plate 224 is used to adjust the polarization direction of the horizontal polarized light to meet the input requirements of the optical fiber amplifier C and then output it externally; based on the first half-wave plate 221 and the Faraday rotator 222 being used to adjust the input light into horizontal polarized light, the transmittance can be improved, and the second polarization beam splitter 223 can filter out the second non-horizontally polarized light R2 in the backward harmful signal light R3, so as to prevent the backward harmful signal light signal from returning to the front-stage amplifier, causing system instability or damage; specifically, the second polarization beam splitter 223 is a Brewster angle thin film polarization beam splitter.

[0032] In some preferred embodiments, Figure 3 and Fig.10 As shown, the optical signal adjustment component 22 also includes a second dichroic mirror 225; the second dichroic mirror 225 is arranged on the optical path between the second polarization beam splitter 223 and the second half-wave plate 224, and is used to transmit the output light of the second polarization beam splitter 223 and filter out the backward pumping light R1; based on the setting of the second dichroic mirror 225, the backward pumping light R1 in the backward harmful signal light R3 generated when the backward pumping amplifier is used can be filtered out to avoid thermal impact on the system and avoid using a traditional pump stripping device. When the traditional pump stripping device uses a large core diameter optical fiber, it will cause high-order modes to be generated, reduce the optical signal mode quality and the time domain contrast of the optical pulse, and increase the system complexity and unreliability.

[0033] Preferably, a signal light anti-reflection film is provided on the input light incident side of the second dichroic mirror 225 for transmitting the signal light in the input light, and a signal light high-pass film is provided on the output side for filtering out the backward pump light R1 in the backward harmful signal light R3 and transmitting the signal light in the input light.

[0034] In some preferred embodiments, Figure 3 and Fig.10 As shown, the optical signal adjustment component 22 also includes a first polarization beam splitter 226; the first polarization beam splitter 226 is arranged on the input side of the first half-wave plate 221, and is used to filter out the first non-horizontal polarized light S2 in the input light; thereby, the polarization extinction ratio of the optical signal is improved, and the backward harmful signal light R3 can be reflected and filtered out; preferably, the first polarization beam splitter 226 is a Brewster angle thin film polarization beam splitter.

[0035] In some preferred embodiments, Figure 1As shown, the optical signal adjustment component 22 also includes a packaging shell 227; a first half-wave plate 221, a Faraday rotator 222, a second polarization beam splitter 223 and a second half-wave plate 224 are installed inside the packaging shell 227, and the packaging shell 227 is provided with a light inlet 2271 and a light outlet 2272; the light inlet 2271 is docked and installed with the light outlet side of the first optical fiber fixture 1; the light outlet 2272 is docked and installed with the light inlet side of the second optical fiber fixture 3; and an opening 2273 and a cover 2274 are provided on the optical path of the reflected light corresponding to the second polarization beam splitter 223, so as to output the non-horizontally polarized light in the reflected backward harmful signal light R3.

[0036] In some preferred embodiments, the first optical fiber fixture 1 includes a first mounting seat 11, a concave lens 12 and a first lens 13; the first mounting seat 11 is mounted on the input side of the packaging module 2, and has a first mounting channel 111 that runs through both sides; one end of the first mounting channel 111 is used to mount the end of the first optical fiber A, and the other end is connected to the packaging module 2, and the concave lens 12 and the first lens 13 are sequentially arranged along the propagation direction of the input light; the concave lens 12 is provided with a light-transmitting hole 121, and the signal light in the input light can be transmitted through the light-transmitting hole 121, and the pump light S1 is scattered by the concave lens 12; the concave surface of the concave lens 12 faces the light-emitting side, and the pump light S1 in the input light is scattered and filtered out by the concave lens 12 with the light-transmitting hole 121, while the signal light is transmitted, which can reduce the thermal effect of the pump light S1 on the system, improve stability, and do not affect the transmission of the signal light. For example, the first mounting channel 111 is arranged along the axis of the first mounting seat 11, thereby reducing the bending and joints of the optical fiber and reducing the transmission loss.

[0037] Preferably, if Figure 4-Figure 6 As shown, the first mounting seat 11 includes a first base 112, a first universal seat 113, a first elastic washer 114, a first bolt 115 and a first top screw 116; the first elastic washer 114 is sandwiched between the first base 112 and the first universal seat 113, and preferably, is sealed and connected to both; the first base 112 is installed on the input side of the packaging module 2, and a first protrusion 117 is provided on the surface facing the first universal seat 113; the first universal seat 113 is connected to the first base 112 by a first bolt 115, and the first universal seat 113 is installed with the first optical The end of the optical fiber A, the concave lens 12 and the first lens 13; one end of the first top screw 116 passes through the first universal seat 113 and then abuts against the first protrusion 117 to adjust the direction of the output end of the first optical fiber A; based on the first universal seat 113 and the first base 112, the first elastic gasket 114, the first top screw 116 and the first protrusion 117 cooperate to achieve the direction adjustment of the output end of the first optical fiber A to provide coupling efficiency and further reduce the insertion loss, so that the insertion loss is less than 0.7dB, and the insertion loss of the commonly used MFA (mode field adapter) is about 1dB.

[0038] Further preferably, the number of the first bolts 115 is multiple, such as 2, 3, 4, etc., to improve the stability of the installation; the first top screw 116 and the first protrusion 117 correspond one to one, and are multiple, such as 2, 3, 4, etc., to achieve multi-directional adjustment, further improving the coupling efficiency, which can reach 95%; preferably, the first bolt 115, the first top screw 116 and the first protrusion 117 are three, alternately arranged, and distributed in an array along the optical path of the first optical fiber A as the axis; if the first base 112 and the first universal seat 113 are connected at the flange pair structure, the first bolt 115, the first top screw 116 and the first protrusion 117 are respectively arranged on the flange.

[0039] Further preferably, the first protrusion 117 is in tangential contact with the end of the first top screw 116, thereby avoiding radial displacement of the first protrusion 117 and the first top screw 116 caused by large-area contact, and even causing the first optical fiber A to produce a radial position, thereby reducing the coupling efficiency. Preferably, the surface where the first protrusion 117 contacts the end of the first top screw 116 is a curved surface.

[0040] In some preferred embodiments, the concave lens 12 and the first lens 13 are respectively installed in the first installation channel 111 through the first retaining ring 118. If the first retaining ring 118 is screwed to the inner wall of the first retaining ring 118, the concave lens 12 or the first lens 13 can be clamped and fixed by setting two first retaining rings 118; the concave lens 12 can also be pressed against the step surface of the first installation channel 111 through the first retaining ring 118.

[0041] In some preferred embodiments, the first mounting seat 11 also includes a first optical fiber clamp 14 and a first fixing screw 15; one end of the first optical fiber clamp 14 is located in the first mounting channel 111, preferably with a clearance fit; and has a first optical fiber mounting channel 141 that runs through both sides; the first optical fiber mounting channel 141 is used to detachably install the first optical fiber A, and the end located in the first mounting channel 111 has a first accommodating portion 142 for accommodating the end cap of the first optical fiber A; one end of the first fixing screw 15 passes through the side wall of the first mounting seat 11 and abuts against the first optical fiber clamp 14 to fix the position of the first optical fiber clamp 14; based on the first optical fiber A being installed on the first optical fiber clamp 14, and the first optical fiber clamp 14 and the first mounting seat 11 being detachable, it is convenient to replace the optical fiber, and the way in which the optical fiber end cap is accommodated in the first accommodating portion 142 can be applied to optical fibers of different specifications, thereby improving the scope of application and compatibility; for example, end caps of the same specification are adopted, preferably, the end caps can be selected as SMA905 connectors to have a higher damage threshold.

[0042] In some preferred embodiments, Figure 7-Figure 9As shown, the second optical fiber fixing member 3 includes a second mounting seat 31 and a second lens 32; the second mounting seat 31 is installed on the input side of the packaging module 2, and has a second mounting channel 311 running through both sides; one end of the second mounting channel 311 is used to install the end of the second optical fiber B, and the other end is connected to the packaging module 2 and is provided with a second lens 32; the second lens 32 is used to focus the output light of the packaging module 2 and input it into the second optical fiber B.

[0043] Preferably, the second mounting seat 31 includes a second base 312, a second universal seat 313, a second elastic gasket 314, a second bolt 315 and a second top screw 316; the second elastic gasket 314 is sandwiched between the second base 312 and the second universal seat 313, and preferably, is sealed and connected to both; the second base 312 is installed on the input side of the packaging module 2, and a second protrusion 317 is provided on the surface facing the second universal seat 313; the second universal seat 313 is connected to the second base 312 by a second bolt 315, and the second universal seat 313 is installed with the end of the second optical fiber B and the second lens 32; one end of the second top screw 316 passes through the second universal seat 313 and then abuts against the second protrusion 317 to adjust the orientation of the output end of the second optical fiber B; based on the fact that the orientation of the output end of the second optical fiber B can be changed, the coupling efficiency can be improved, especially when the orientation of the end of the first optical fiber A can also be changed, the coupling efficiency can be further improved and the energy loss can be reduced.

[0044] Further preferably, the number of the second bolts 315 is multiple, such as 2, 3, 4, etc., to improve the stability of the installation; the second top screw 316 and the second protrusion 317 correspond one to one, and are multiple, such as 2, 3, 4, etc., to achieve multi-directional adjustment, further improving the coupling efficiency, which can reach 95%; preferably, the second bolt 315, the second top screw 316 and the second protrusion 317 are three, alternately arranged, and distributed in an array along the optical path of the second optical fiber A as the axis; if the second base 312 and the second universal seat 313 are connected at the joint to form a flange pair structure, the second bolt 315, the second top screw 316 and the second protrusion 317 are respectively arranged on the flange.

[0045] Further preferably, the second protrusion 317 is in tangential contact with the end of the second top screw 316; thereby, radial displacement of the second protrusion 317 and the second top screw 316 caused by large-area contact is avoided, and even radial position of the second optical fiber A is caused, thereby reducing coupling efficiency. Preferably, the surface where the second protrusion 317 contacts the end of the second top screw 316 is an arc surface. Preferably, the surface where the second protrusion 317 contacts the end of the second top screw 316 is an arc surface.

[0046] In some preferred embodiments, the second lens 32 is installed in the second installation channel 311 through the second retaining ring 318. If the second retaining ring 318 is screwed to the inner wall of the second retaining ring 318, the second lens 32 can be pressed against the step surface of the second installation channel 311 through the second retaining ring 318.

[0047] In some preferred embodiments, Figure 7 and Figure 8 As shown, the second mounting seat 31 further includes a second optical fiber clamp 33 and a second fixing screw 34; one end of the second optical fiber clamp 33 is located in the second mounting channel 311, preferably with clearance fit; and has a second optical fiber mounting channel 331 that runs through both sides; the second optical fiber mounting channel 331 is used to detachably mount the second optical fiber B, and the end located in the second mounting channel 311 has a second accommodating portion 332 for accommodating the end cap of the second optical fiber A; one end of the second fixing screw 34 passes through the side wall of the second mounting seat 31 and then abuts against the second optical fiber clamp 33 to fix the position of the second optical fiber clamp 33. Based on the installation of the second optical fiber A on the second optical fiber clamp 33, and the detachability between the second optical fiber clamp 33 and the second mounting seat 31, it is convenient to replace the optical fiber, and the second accommodating portion 332 accommodates the optical fiber end cap, which can be applied to optical fibers of different specifications, thereby improving the scope of application and compatibility; for example, using end caps of the same specification, preferably, the end caps can be selected as SMA905 connectors to have a higher damage threshold.

[0048] The working process of the device of the present invention is described below: The input light is collimated by the first lens 13 and then enters the first dichroic mirror 21. The first dichroic mirror 21 reflects the pump light S1 in the input light, and the signal light is transmitted into the first polarization beam splitter 226. The first polarization beam splitter 226 filters out the first non-horizontal polarized light S2 in the input light and then enters the first polarizer 221 and the Faraday rotator 222. The polarization direction is rotated to horizontal polarization through the two, and then enters the second polarization beam splitter 223. The second polarization beam splitter 223 filters out the vertical polarized light in the input light. The horizontal polarized light is transmitted into the second dichroic mirror 225, and then the polarization direction is rotated to conform to the second polarizer 224, and then the signal light is focused by the second lens 32 and enters the second optical fiber B, and finally enters the backward pump amplifier C. The backward harmful light generated by the backward pump amplifier C is collimated by the second lens 32 and the second polarizer 224 before entering the second dichroic mirror 225, which filters out the backward pump light R1. The light then enters the second polarization beam splitter 223, which filters out the second non-horizontal polarized light R2 in the backward harmful light. The horizontally polarized light is rotated in polarization direction by the Faraday rotator 222 and the first polarizer 221 to form vertically polarized light, which is reflected and eliminated by the first polarization beam splitter 226.

[0049] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A mode matching device based on spatial coupling, characterized in that: It includes a first optical fiber fixing part, a packaging module and a second optical fiber fixing part; The first optical fiber fixing member is installed at the input side of the packaging module and is used to install the first optical fiber and adjust the input light before inputting it into the packaging module; The second optical fiber fixing member is installed at the output side of the packaging module, and is used to install the second optical fiber and adjust the output light of the packaging module and input it into the second optical fiber; The packaging module includes a first dichroic mirror and an optical signal adjustment component arranged in sequence along the light propagation direction; The first dichroic mirror is used to filter out the pump light in the input light; The optical signal adjustment component is used to adjust the output light of the first dichroic mirror to meet the input requirements of the optical fiber amplifier and then output it externally.

2. The mode matching device based on spatial coupling according to claim 1, characterized in that: The optical signal adjustment component comprises a first half-wave plate, a Faraday rotator, a second polarization beam splitter and a second half-wave plate which are sequentially arranged along the light propagation direction; The first half-wave plate and the Faraday rotator are used to adjust the input light into horizontally polarized light; The second polarization beam splitter is used to transmit the horizontally polarized light in the output light of the Faraday rotator into the second half-wave plate; The second half-wave plate is used to adjust the polarization direction of the horizontally polarized light to meet the input requirements of the optical fiber amplifier before outputting it.

3. The mode matching device based on spatial coupling according to claim 2, characterized in that: The optical signal adjustment assembly also includes a second dichroic mirror; The second dichroic mirror is disposed on the optical path between the second polarization beam splitter and the second half-wave plate, and is used for transmitting the output light of the second polarization beam splitter and filtering out the backward pump light.

4. The mode matching device based on spatial coupling according to claim 3, characterized in that: The input light incident side of the second dichroic mirror is provided with a signal light anti-reflection film, and the output side is provided with a signal light high-pass film; The signal light high-pass film is used to filter out the backward pump light and transmit the signal light in the input light.

5. The mode matching device based on spatial coupling according to claim 2, characterized in that: The optical signal adjustment component also includes a first polarization beam splitter; The first polarization beam splitter is arranged at the input side of the first half-wave plate and is used for filtering out non-horizontally polarized light in the input light.

6. The mode matching device based on spatial coupling according to claim 2, characterized in that: The optical signal adjustment component also includes a packaging shell; The first half-wave plate, the Faraday rotator, the second polarization beam splitter and the second half-wave plate are installed inside the packaging shell, and the packaging shell is provided with a light inlet and a light outlet; The light inlet is butt-jointed with the light emitting side of the first optical fiber fixing member; The light outlet is butt-jointed with the light incident side of the second optical fiber fixing member.

7. The mode matching device based on spatial coupling according to claim 1, characterized in that: The incident side of the input light of the first dichroic mirror is provided with a signal light high-pass film for signal light transmission and pump light reflection, and the output side is provided with a signal light anti-reflection film.

8. The mode matching device based on spatial coupling according to claim 1, characterized in that: The first optical fiber fixing member includes a first mounting seat, a concave lens and a first lens; The first mounting seat is installed on the input side of the packaging module and has a first mounting channel running through both sides; One end of the first installation channel is used to install the end of the first optical fiber, and the other end is connected to the packaging module, and the concave lens and the first lens are sequentially arranged along the propagation direction of the input light; The concave lens is provided with a light-transmitting hole, and the signal light in the input light can be transmitted through the light-transmitting hole, and the pump light is scattered by the concave lens.

9. The mode matching device based on spatial coupling according to claim 8, characterized in that: The first mounting seat comprises a first base, a first universal seat, a first elastic washer, a first bolt and a first top screw; The first elastic washer is sandwiched between the first base and the first universal seat; The first base is installed on the input side of the packaging module, and a first protrusion is provided on the surface facing the first universal seat; The first universal seat is connected to the first base through the first bolt, and the first universal seat is provided with the end of the first optical fiber, the concave lens and the first lens; One end of the first top screw passes through the first universal seat and then abuts against the first protrusion to adjust the direction of the first optical fiber output end.

10. The mode matching device based on spatial coupling according to claim 9, characterized in that: The first protrusion is in tangential contact with the end of the first top screw.

11. The mode matching device based on spatial coupling according to claim 8, characterized in that: The first mounting seat also includes a first optical fiber clamp and a first fixing screw; One end of the first optical fiber clamp is located in the first installation channel and has a first optical fiber installation channel running through both sides; The first optical fiber installation channel is used to detachably install the first optical fiber, and the end portion located in the first installation channel has a first receiving portion for receiving an end cap of the first optical fiber; One end of the first fixing screw passes through the side wall of the first mounting seat and abuts against the first optical fiber clamp to fix the position of the first optical fiber clamp.

12. The mode matching device based on spatial coupling according to claim 1, characterized in that: The second optical fiber fixing member includes a second mounting seat and a second lens; The second mounting seat is mounted on the input side of the packaging module and has a second mounting channel running through both sides; One end of the second installation channel is used to install the end of the second optical fiber, and the other end is connected to the packaging module and is provided with the second lens; The second lens is used to focus the output light of the packaging module and then input it into the second optical fiber.

13. The mode matching device based on spatial coupling according to claim 12, characterized in that: The second mounting seat comprises a second base, a second universal seat, a second elastic washer, a second bolt and a second top screw; The second elastic washer is sandwiched between the second base and the second universal seat; The second base is installed on the input side of the packaging module, and a second protrusion is provided on the surface facing the second universal seat; The second universal seat is connected to the second base through the second bolt, and the second universal seat is installed with the end of the second optical fiber and the second lens; One end of the second top screw passes through the second universal seat and then abuts against the second protrusion to adjust the direction of the second optical fiber output end.

14. The mode matching device based on spatial coupling according to claim 13, characterized in that: The second protrusion is in tangential contact with the end of the second top screw.

15. The mode matching device based on spatial coupling according to claim 12, characterized in that: The second mounting base also includes a second optical fiber clamp and a second fixing screw; One end of the second optical fiber clamp is located in the second installation channel and has a second optical fiber installation channel running through both sides; The second optical fiber installation channel is used for detachably installing the second optical fiber, and the end portion located in the second installation channel has a second receiving portion for receiving an end cap of the second optical fiber; One end of the second fixing screw passes through the side wall of the second mounting seat and abuts against the second optical fiber clamp to fix the position of the second optical fiber clamp.

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