Three-band mode multiplexing self-matching type photon lantern and manufacturing method

Abstract

The invention provides a triple-band mode multiplexing self-matching type photon lantern and a manufacturing method, and belongs to the field of optical communication, and the photon lantern comprises an optical fiber array, a transition area and a few-mode port which are connected in sequence; the optical fiber array is a preset number of 980nm single-mode optical fibers containing claddings, a 1310nm few-mode optical fiber containing a cladding and a 1550nm few-mode optical fiber containing a cladding, which are arranged in a quartz capillary and are subjected to heat insulation tapering to a preset stretching length according to a preset stretching ratio, and the shape of the part is not changed; the transition area is a part with the shape changed after tapering, and the die-less port is a port part with the shape changed after tapering. The photon lantern can realize 980nm wavelength mode selective conversion, 1550nm and 1310nm wavelength mode maintenance and low-loss closed-loop transmission, can be used for constructing an optical fiber annular laser cavity, realizes direct oscillation and output of a plurality of high-order modes in the full-few-mode optical fiber annular laser cavity, and avoids the problem of incompatibility between a single mode and a few mode.

Description

Technical Field

[0001] The present invention relates to the field of optical communications, and in particular to a three-band mode multiplexing self-matching photon lantern device and a manufacturing method thereof. Background Art

[0002] At present, the communication system based on single-mode optical fiber is infinitely close to the upper limit of transmission capacity and cannot meet the development needs of the economy and society. The high-order transverse modes in optical fiber have orthogonality, unique spatial intensity and polarization distribution characteristics. Through the method of mode division multiplexing, the spatial dimension of information transmission can be expanded, breaking through the bottleneck of the transmission capacity of the existing single-mode optical fiber communication system, and fully meeting the rapidly growing bandwidth demand in the 5G era.

[0003] In order to achieve controllable excitation of high-order modes in optical fibers, a variety of mode conversion devices have been developed, including few-mode fiber gratings, asymmetric fiber couplers, fiber staggered structures, and photonic lanterns.

[0004] Fiber mode conversion devices are often used in fiber laser systems to generate high-order mode lasers. In fiber communication systems based on mode division multiplexing, high-order mode lasers are located at the front end of the system. The quality of the beams they generate and the number of supported modes play a decisive role in communication quality and bandwidth. Among the above-mentioned mode conversion devices, the mode-selective photon lantern is a relatively ideal mode conversion device, but when used in fiber laser systems, there is an incompatibility problem between single-mode and few-mode. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a three-band mode multiplexing self-matching photon lantern and a manufacturing method and device.

[0006] The present invention provides a three-band mode multiplexing self-matching photon lantern, comprising: an optical fiber array, a transition zone and a few-mode port connected in sequence; the optical fiber array is a portion of a preset number of 980nm single-mode optical fibers containing cladding, a 1310nm few-mode optical fiber containing cladding and a 1550nm few-mode optical fiber containing cladding placed in a quartz capillary, and the shape remains unchanged after adiabatic tapering to a preset stretched length according to a preset stretching ratio; the transition zone is a portion whose shape changes after tapering, and the few-mode port is a port portion whose shape changes after tapering; wherein the stretching ratio is determined according to the normalized frequency of the few-mode optical fiber so that the few-mode port generates a linearly polarized LP mode, and the preset number corresponds to the number of modes applied by the photon lantern.

[0007] According to a three-band mode multiplexing self-matching photonic lantern provided by the present invention, the preset number includes 3, 6, 10 and 15.

[0008] According to a three-band mode multiplexing self-matching photonic lantern provided by the present invention, the optical fiber arrangement before tapering is as follows: when the periphery of the overall array of the few-mode optical fiber and the single-mode optical fiber is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fiber are arranged at equal intervals.

[0009] According to a three-band mode multiplexing self-matching photonic lantern provided by the present invention, the LP modes are LP01 mode, LP11a mode and LP11b mode respectively. Correspondingly, the preset number is 3, and the optical fiber arrangement before tapering is a regular pentagonal arrangement of two adjacent few-mode optical fibers.

[0010] According to a three-band mode multiplexing self-matching photon lantern provided by the present invention, the core and cladding refractive indices of the 980nm single-mode optical fiber are 1.45 and 1.444 respectively, the core and cladding tube refractive indices of the 1310nm few-mode optical fiber are 1.4685 and 1.444 respectively, the core and cladding tube refractive indices of the 1550nm few-mode optical fiber are 1.4669 and 1.444 respectively, and the refractive index of the quartz capillary is 1.438.

[0011] According to a three-band mode multiplexing self-matching photon lantern provided by the present invention, the core and cladding sizes of two 980nm single-mode optical fibers are 4μm and 125μm respectively, the core and cladding sizes of another 980nm single-mode optical fiber are 6μm and 125μm respectively, the core and cladding sizes of the 1310nm few-mode optical fiber are 15μm and 125μm respectively, and the core and cladding sizes of the 1550nm few-mode optical fiber are 15μm and 125μm respectively.

[0012] According to a three-band mode multiplexing self-matching photon lantern provided by the present invention, the inner diameter of the quartz capillary is 400 μm and the outer diameter is 415 μm.

[0013] The present invention also provides a method for manufacturing a three-band mode multiplexing self-matching photon lantern, comprising: placing a preset number of 980nm single-mode optical fibers containing cladding, a 1550nm few-mode optical fiber containing cladding, and a 1310nm few-mode optical fiber containing cladding in a quartz capillary; adiabatically tapering the quartz capillary with the built-in optical fiber to a preset stretched length according to a preset stretching ratio; wherein the stretching ratio is determined based on the normalized frequency of the few-mode optical fiber so that the few-mode port generates an LP mode, the few-mode port being the port portion whose shape is changed after tapering, and the preset number corresponds to the number of modes applied to the photon lantern.

[0014] According to a method for manufacturing a three-band mode multiplexing self-matching photon lantern provided by the present invention, the optical fiber arrangement before tapering is as follows: when the periphery of the overall array of the few-mode optical fiber and the single-mode optical fiber is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fiber are arranged at equal intervals.

[0015] According to a method for manufacturing a three-band mode multiplexing self-matching photon lantern provided by the present invention, the LP modes are LP 01 Mode, LP 11a and LP 11b mode, accordingly, the preset number is 3, and the optical fiber arrangement before tapering is a regular pentagonal arrangement of two adjacent few-mode optical fibers.

[0016] The present invention also provides a three-band mode multiplexing fiber laser, comprising: a 980nm laser and any one of the three-band mode multiplexing self-matching photon lanterns described above; the 980nm laser is connected to each 980nm single-mode optical fiber of the photon lantern, and the pump light injected from different 980nm single-mode optical fibers passes through the photon lantern to achieve selective excitation of the fundamental mode to a higher-order linear polarization mode; the 1310nm few-mode optical fiber and the 1550nm few-mode optical fiber of the photon lantern are connected to the few-mode port through an optical switch to form a ring laser cavity, and the few-mode erbium-doped optical fiber is connected to the ring laser cavity as a gain optical fiber to convert the wavelength running in the cavity to 1550nm or 1310nm.

[0017] The three-band mode multiplexing self-matching photon lantern and the manufacturing method device provided by the present invention can realize 980 / 1550 / 1310nm three-band mode multiplexing, that is, 980nm wavelength mode selective conversion, 1550nm and 1310nm wavelength mode retention, low-loss closed-loop transmission, and can be used to construct a full multimode (few-mode) fiber ring laser cavity to realize the direct oscillation and output of multiple high-order mode lasers in the full few-mode fiber ring laser cavity, and one device can realize the high-order mode output generation of three wavelengths, thereby providing an effective device for the generation of multiple 1310nm and 1550nm high-order mode lasers, getting rid of the dependence on wavelength division multiplexers, and avoiding the problem of incompatibility between single-mode and few-mode in fiber lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1It is a structural schematic diagram of a three-band mode multiplexing self-matching photon lantern provided by the present invention;

[0020] Figure 2 It is a schematic diagram of the few-mode end face of a novel self-matching photon lantern with three-mode selectivity for 980nm laser transmission provided by the present invention;

[0021] Figure 3 It is a schematic diagram of the change of the effective refractive index of the mode corresponding to the wavelength of 980nm provided by the present invention;

[0022] Figure 4 It is a schematic diagram of the simulation results of the mode field evolution corresponding to the three-mode selective novel self-matching photon lantern for 980nm laser transmission provided by the present invention under different taper ratio conditions;

[0023] Figure 5 It is a schematic diagram of the few-mode end face of a novel self-matching photon lantern with three-mode selectivity for 1550nm laser transmission provided by the present invention;

[0024] Figure 6 It is a schematic diagram of the change of the effective refractive index of the mode corresponding to the wavelength of 1550nm provided by the present invention;

[0025] Figure 7 It is a schematic diagram of the simulation results of the mode field evolution corresponding to the three-mode selective novel self-matching photon lantern for 1550nm laser transmission provided by the present invention under different taper ratio conditions;

[0026] Figure 8 It is a schematic diagram of the few-mode end face of a novel self-matching photon lantern with three-mode selectivity for 1310nm laser transmission provided by the present invention;

[0027] Fig. 9 It is a schematic diagram of the change of the effective refractive index of the mode corresponding to the wavelength of 1310nm provided by the present invention;

[0028] Fig.10 It is a schematic diagram of the simulation results of the mode field evolution corresponding to the three-mode selective novel self-matching photon lantern of 1310nm laser transmission provided by the present invention under different taper ratio conditions;

[0029] Fig.11 It is a schematic flow chart of a method for manufacturing a three-band mode multiplexing self-matching photon lantern provided by the present invention;

[0030] Fig.12 It is a schematic diagram of a three-band mode multiplexing fiber laser provided by the present invention;

[0031] Explanation of the reference numerals: 1, optical fiber array; 2, transition zone; 3, few-mode port; 1-1, 980 nm single-mode optical fiber; 1-2, 1310 nm few-mode optical fiber; 1-3, 1550 nm few-mode optical fiber; 100 (101, 102), 980 nm single-mode optical fiber. DETAILED DESCRIPTION

[0032] 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 drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the 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.

[0033] The present invention provides a novel photon lantern device and a manufacturing method, which aims to solve the incompatibility problem between single-mode and multi-mode systems when photon lanterns are directly used in fiber lasers. By designing a novel photon lantern, it can be fully involved in the construction of a full few-mode fiber ring cavity laser in terms of structure and function, simplifying the system structure and improving the mode conversion efficiency.

[0034] Its 980 / 1310 / 1550nm three-band mode multiplexing characteristics make it suitable for building fiber lasers, getting rid of the dependence on wavelength division multiplexers. In addition, its matching characteristics of input 1550nm few-mode fiber or 1310nm few-mode fiber and output (multimode) few-mode port can be used to build a full few-mode fiber ring laser cavity, realizing the direct oscillation and output of multiple high-order mode lasers in the full few-mode fiber ring laser cavity.

[0035] Combine the following Figure 1-Figure 12 The present invention describes a three-band mode multiplexing self-matching photon lantern and a method for making the same. Figure 1 Schematic diagram of the structure of the three-band mode multiplexing self-matching photon lantern provided by the present invention. Figure 1 As shown, the present invention provides a three-band mode multiplexing self-matching photon lantern, comprising: an optical fiber array 1, a transition zone 2 and a few-mode port 3 connected in sequence; the optical fiber array 1 is a 980nm single-mode optical fiber 1-1 with a preset number of claddings, a 1310nm few-mode optical fiber 1-2 with a cladding and a 1550nm few-mode optical fiber 1-3 with a cladding placed in a quartz capillary, and the shape remains unchanged after adiabatic tapering to a preset stretched length according to a preset stretching ratio; the transition zone 2 is a part whose shape changes after tapering, and the few-mode port 3 is a port part whose shape changes after tapering; wherein the stretching ratio is determined according to the normalized frequency of the few-mode optical fiber, so that the few-mode port generates a linearly polarized LP mode, and the preset number corresponds to the number of modes applied by the photon lantern.

[0036] The optical fiber array 1 is placed in a low-refractive-index quartz sleeve in a certain arrangement, and a transition zone 2 is formed by adiabatic melting and taper. The optical fiber array 1 gradually merges into one during the adiabatic taper process, and the 980nm single-mode fiber core, 1310nm few-mode fiber, and 1550nm few-mode fiber core gradually become thinner until they finally lose their ability to bind light. The original cladding in the optical fiber array 1 becomes the new fiber core, and the low-refractive-index quartz sleeve outside becomes the new cladding. When the taper is stretched to a certain taper length according to the preset taper ratio, the taper is stopped, and finally a new few-mode waveguide is formed, whose parameters are similar to those of the 1310nm few-mode fiber and the 1550nm few-mode fiber, and supports mode closed-loop low-loss transmission.

[0037] The few-mode port 3 formed by the adiabatic taper can be matched with the 1310nm few-mode fiber 1-2 and the 1550nm few-mode fiber 1-3 to achieve transmission of the same mode. Light with a wavelength of 980nm is injected from different optical fibers in the 980nm single-mode fiber cluster 1-1. After passing through the new photon lantern, the 980nm light wave can complete the conversion from the fundamental mode to the specific mode. Light with a wavelength of 1310nm is input from the 1310nm few-mode fiber 1-2. After evolving through the new photon lantern, the mode morphology can be maintained and low-loss transmission can be achieved, and the 1310nm few-mode fiber 1-2 is matched with the few-mode port 3. Light with a wavelength of 1550nm is input from the 1550nm few-mode fiber 1-3. After evolving through the new photon lantern, the mode morphology can be maintained and low-loss transmission can be achieved, and the 1550nm few-mode fiber 1-3 is matched with the few-mode port 3.

[0038] The three-band mode multiplexing self-matching photon lantern of the present invention can realize 980 / 1550 / 1310nm three-band mode multiplexing, that is, 980nm wavelength mode selective conversion, 1550nm and 1310nm wavelength mode retention, low-loss closed-loop transmission, and can be used to construct a full multimode (few-mode) fiber ring laser cavity to realize the direct oscillation and output of multiple high-order mode lasers in the full few-mode fiber ring laser cavity, and one device can realize the high-order mode output generation of three wavelengths, thereby providing an effective device for the generation of multiple 1310nm and 1550nm high-order mode lasers, getting rid of the dependence on wavelength division multiplexers, and avoiding the problem of incompatibility between single-mode and few-mode in fiber lasers.

[0039] The novel photon lantern of the present invention is highly practical, has low manufacturing cost, simple use process, and much higher mode conversion efficiency than other devices. It can also achieve low-loss insertion in the laser system, and is suitable for large-scale promotion and use, generating certain economic value.

[0040] In one embodiment, the preset number includes 3, 6, 10 and 15.

[0041] In one embodiment, the optical fiber arrangement before tapering is as follows: when the periphery of the overall array of the few-mode optical fiber and the single-mode optical fiber is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fiber are arranged at equal intervals.

[0042] When the embodiments of the present invention are arranged, the outer periphery of the optical fiber array is equally spaced and in the form of a regular polygon, so that the effect of generating high-order modes is better.

[0043] In one embodiment, the LP modes are LP01 mode, LP11a mode and LP11b mode respectively. Accordingly, the preset number is 3, and the optical fiber arrangement before tapering is a regular pentagonal arrangement of two adjacent few-mode optical fibers.

[0044] Schematic diagram of the new self-matching photonic lantern with three-mode selectivity Figure 1 As shown. The few-mode port can selectively excite the LP 01 LP 11a With LP 11b There are three linear polarization modes, and the number of single-mode fibers in the corresponding 980nm single-mode fiber cluster is 3. The three 980nm single-mode fibers correspond to Figure 1 100, 101 and 102 in the figure. Correspondingly, the 1310nm few-mode fiber can use three-mode fiber, corresponding to 1-2 in the figure, and the 1550nm few-mode fiber can use three-mode fiber, corresponding to 1-3 in the figure.

[0045] According to the relevant research conclusions on the influence of optical fiber geometric arrangement on mode conversion in photon lanterns, it is necessary to support LP mn The optical fiber array should be arranged in the form of m concentric circles. The number of optical fibers on each ring should be N = 2n. max +1, thereby achieving selective excitation of the modes in the photon lantern. When the mode supported by the photon lantern is LP 01 LP 11a and LP 11b When m=1, n max =1, N=3, three 980nm single-mode optical fibers should be distributed on a ring.

[0046] In the embodiment of the present invention, considering that the three-mode optical fiber used to transmit 1310nm laser and 1550nm laser is also a part of the new photon lantern, but it does not inject 980nm light beam itself, therefore, five optical fibers are arranged in a regular pentagon, and two few-mode optical fibers are arranged adjacent to each other, so as to ensure the selective excitation of the modes in the photon lantern while supporting the functional requirements of the new photon lantern for 980 / 1310 / 1550nm three-band mode multiplexing.

[0047] In one embodiment, the core and cladding refractive indices of the 980nm single-mode optical fiber are 1.45 and 1.444, respectively; the core and cladding refractive indices of the 1310nm few-mode optical fiber are 1.4685 and 1.444, respectively; the core and cladding refractive indices of the 1550nm few-mode optical fiber are 1.4669 and 1.444, respectively; and the refractive index of the quartz capillary is 1.438.

[0048] In one embodiment, the core and cladding sizes of two 980nm single-mode optical fibers are 4μm and 125μm respectively, the core and cladding sizes of another 980nm single-mode optical fiber are 6μm and 125μm respectively, the core and cladding sizes of the 1310nm few-mode optical fiber are 15μm and 125μm respectively, and the core and cladding sizes of the 1550nm few-mode optical fiber are 15μm and 125μm respectively.

[0049] In one embodiment, the inner diameter of the quartz capillary is 400 μm and the outer diameter is 415 μm.

[0050] For the three-mode selective new self-matching photon lantern, the preset parameters of the three 980nm single-mode optical fibers need to be designed differently according to the transmission characteristics of the mode. The embodiment of the present invention adopts a preferred solution with better performance, and the core and cladding refractive indexes of the three 980nm single-mode optical fibers in the three-mode selective new self-matching photon lantern are designed to be 1.45 and 1.444 respectively, among which the core and cladding sizes of the two 980nm single-mode optical fibers are designed to be 4μm and 125μm, which can selectively excite LP 11a and LP 11b mode, another 980nm single-mode fiber core and cladding size are designed to be 6μm and 125μm, and the LP 01 The core and cladding refractive indexes of 1310nm three-mode optical fiber are designed to be 1.4685 and 1.444 respectively, and the core and refractive index sizes are designed to be 15μm and 125μm respectively. The core and cladding refractive indexes of 1550nm three-mode optical fiber are designed to be 1.4669 and 1.444 respectively, and the core and refractive index sizes are designed to be 15μm and 125μm respectively.

[0051] It should be noted that the above optical fiber and cladding dimensions are not conventional choices in the art, but are dimension parameters with better coupling effect set to better match the regular pentagonal arrangement of the five optical fibers in the above embodiment.

[0052] When the claddings of the above five optical fibers are all 125 μm, the inner diameter of the outermost low-refractive-index quartz capillary is about 400 μm, the outer diameter thereof is designed to be 415 μm, and the refractive index is designed to be 1.438.

[0053] In one embodiment, the stretching ratio is 0.1.

[0054] According to the above parameters, the three-mode selective new self-matching photon lantern is simulated and set to simulate the light field evolution process of the 980nm light wave inside the three-mode selective new self-matching photon lantern. Figure 2 Schematic diagram of the three-mode selective new self-matching photon lantern few-mode end face for 980nm laser transmission, where the highlighted parts are the cores of 980nm single-mode optical fibers 100, 101 and 102, and the core sizes of 100 and 101 are the same (4μm), corresponding to the excitation LP 11a With LP 11b mode, the core of 102 (6μm) corresponds to the excitation LP 01 model. Figure 3 When the taper ratio reaches 0.1, the fundamental mode in the original 100, 101 and 102 single-mode fibers excites the corresponding LP at the minority-mode port. 01 LP 11a With LP 11b mode to achieve selective excitation of the 980nm band mode. Figure 4 Schematic diagram of the simulation results of mode field evolution of the new three-mode selective self-matching photonic lantern for 980nm laser transmission under different taper ratios.

[0055] According to the above parameters, the simulation setting of the new three-mode selective self-matching photon lantern is carried out to simulate the light field evolution process of the 1550nm light wave inside the new three-mode selective self-matching photon lantern. Figure 5 Schematic diagram of the new self-matching photonic lantern few-mode end face for three-mode selectivity for 1550nm laser transmission. The highlighted part is the 1550nm few-mode fiber core after tapering. Figure 6 The change of the effective refractive index of the 1550nm mode with the taper ratio is shown. When the taper ratio is greater than 0.3, the 1550nm three-mode fiber can stably transmit LP 01 and LP 11 mode. As the taper ratio decreases, LP 11 The mode first leaks into the cladding. When the taper ratio is lower than 0.15, the core can no longer guide the mode transmission, and the cladding of the fiber array becomes the new "core" and guides the mode to transmit stably. Figure 7 When the taper ratio reaches 0.05, the LP injected into the original 1550nm three-mode fiber 01 LP 11a With LP 11b mode, which can be matched with the initial mode field at the few-mode port, that is, the 1550nm mode can maintain its mode morphology through the new three-mode selective photon lantern, and low-loss closed-loop transmission can be achieved when connected to the few-mode optical fiber.

[0056] According to the above parameters, the simulation setting of the new three-mode selective self-matching photon lantern is carried out to simulate the light field evolution process of the 1310nm light wave inside the new three-mode selective self-matching photon lantern. Figure 8 Schematic diagram of the new self-matching photonic lantern few-mode end face for three-mode selectivity for 1310nm laser transmission. The highlighted part is the 1310nm few-mode fiber core after tapering. Fig. 9 The variation of the effective refractive index of the 1310nm mode with the taper ratio is shown. When the taper ratio is greater than 0.3, the 1310nm three-mode fiber can stably transmit the LP01 and LP11 modes. As the taper ratio decreases, the LP11 mode leaks into the cladding first. When the taper ratio is lower than 0.1, the core can no longer guide the mode transmission, and the cladding of the fiber array becomes the new "core" and guides the mode to transmit stably. Fig.10 In the experiment, when the taper ratio reaches 0.05, the LP01, LP11a and LP11b modes injected into the original 1310nm three-mode optical fiber can match the initial mode field at the few-mode port. That is, the 1310nm mode can maintain its mode morphology through the new self-matching photonic lantern with three-mode selectivity, and low-loss closed-loop transmission can be achieved when connected to the few-mode optical fiber.

[0057] The new photon lantern can solve the incompatibility problem between single mode and few mode when conventional photon lanterns are used to construct fiber lasers. The few-mode fiber added to the fiber array can match the few-mode port formed by the taper to achieve closed-loop transmission of the 1550nm / 1310nm mode. In addition, the new photon lantern has the characteristics of 980 / 1550 / 1310nm three-band mode multiplexing, and can be used to construct fiber lasers to get rid of the dependence on wavelength division multiplexing devices. The new photon lantern can be used to construct a full few-mode fiber ring cavity laser to generate high-order mode lasers in the 1550nm and 1310nm bands.

[0058] The following describes the method for manufacturing a three-band mode multiplexing self-matching photon lantern provided by the present invention. The method for manufacturing the three-band mode multiplexing self-matching photon lantern described below and the three-band mode multiplexing self-matching photon lantern described above can be referenced to each other.

[0059] Fig.11 Schematic diagram of the process of manufacturing a three-band mode multiplexing self-matching photon lantern provided by the present invention, such as Fig.11 As shown, the method for manufacturing the three-band mode multiplexing self-matching photon lantern includes:

[0060] 1101. Place a preset number of 980 nm single-mode optical fibers containing claddings, a 1550 nm few-mode optical fiber containing claddings, and a 1310 nm few-mode optical fiber containing claddings in a quartz capillary;

[0061] 1102. Adiabatically tapering the quartz capillary tube with the built-in optical fiber to a preset stretching length according to a preset stretching ratio;

[0062] Among them, the stretching ratio is determined according to the normalized frequency of the few-mode optical fiber so that the few-mode port generates an LP mode, and the few-mode port is the port part whose shape is changed after tapering, and the preset number corresponds to the number of modes applied by the photon lantern.

[0063] In one embodiment, the optical fiber arrangement before tapering is as follows: when the periphery of the overall array of the few-mode optical fiber and the single-mode optical fiber is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fiber are arranged at equal intervals.

[0064] In one embodiment, the LP modes are LP01 mode, LP11a mode and LP11b mode, respectively. Accordingly, the preset number is 3, and the optical fiber arrangement before tapering is a regular pentagonal arrangement of two adjacent few-mode optical fibers. The method embodiment provided in the embodiment of the present invention is to realize the above-mentioned device embodiments. For specific processes and detailed contents, please refer to the above-mentioned device embodiments, which will not be repeated here.

[0065] The method for manufacturing a three-band mode multiplexing self-matching photon lantern provided in an embodiment of the present invention has the same implementation principle and technical effects as those of the aforementioned three-band mode multiplexing self-matching photon lantern embodiment. For the sake of brief description, for matters not mentioned in the embodiment of the method for manufacturing a three-band mode multiplexing self-matching photon lantern, reference may be made to the corresponding contents in the aforementioned three-band mode multiplexing self-matching photon lantern embodiment.

[0066] Fig.12 Schematic diagram of the structure of the three-band mode multiplexing fiber laser provided by the present invention, such as Fig.12 As shown, the three-band mode multiplexing fiber laser includes: a 980nm laser and any one of the three-band mode multiplexing self-matching photon lanterns described above; the 980nm laser is connected to each 980nm single-mode optical fiber of the photon lantern, and the pump light injected by different 980nm single-mode optical fibers passes through the photon lantern to achieve selective excitation of the fundamental mode to a higher-order linear polarization mode; the 1310nm few-mode optical fiber and the 1550nm few-mode optical fiber of the photon lantern are connected to the few-mode port through an optical switch to form a ring laser cavity, and the few-mode erbium-doped optical fiber is connected to the ring laser cavity as a gain optical fiber to convert the wavelength running in the cavity to 1550nm or 1310nm.

[0067] Taking the three-mode selective new self-matching photon lantern as an example, the three-mode selective new self-matching photon lantern is used to construct a full few-mode fiber ring cavity continuous light laser to achieve 1550nm and 1310nm high-order mode laser output. Specifically, the 980nm single-mode fiber cluster of the new photon lantern can be connected to the 980nm laser through an optical switch. After the pump light injected by different optical fibers in the 980nm single-mode fiber cluster passes through the new photon lantern, the fundamental mode is selectively excited to a specific high-order mode. The 1550nm few-mode fiber and the 1310nm few-mode fiber of the new photon lantern are connected to the few-mode port through an optical switch to form a ring laser cavity. The output wavelength can be selected as 1310nm or 1550nm by the wavelength of the signal light input into the ring cavity. The few-mode erbium-doped fiber is introduced into the ring cavity as a gain fiber to convert the wavelength running in the cavity to 1550nm or 1310nm. In addition, isolators, polarization controllers, few-mode fiber splitters and other devices can be introduced into the system to ensure the operation, regulation and output of 1550nm or 1310nm high-order mode lasers.

[0068] Specifically, an isolator is introduced into the system to ensure unidirectional transmission of light; a polarization controller is introduced to adjust the polarization state of the mode field and generate a vector beam. A few-mode fiber beam splitter is introduced into the ring cavity to achieve 1310 / 1550nm high-order transverse mode laser output. A spectrum analyzer is used to measure the wavelength and spectral characteristics of the output laser, and a 1550nm CCD is used to observe the light field distribution of the output laser.

[0069] In summary, the present invention constructs a self-matching photon lantern by adding two few-mode fibers to the optical fiber array of the photon lantern, which can serve the generation of multiple high-order transverse modes of 1310 / 1550nm. The self-matching photon lantern can realize 980 / 1310 / 1550nm three-band mode multiplexing, and the 980nm pump light input through different single-mode fibers can be selectively converted into the corresponding high-order transverse mode, and the self-cavity characteristics of the few-mode fiber can enable low-loss closed-loop transmission of 1310nm and 1550nm high-order transverse modes.

[0070] The research on self-matching photon lanterns in the present invention enriches the types and functions of photon lanterns. With the further in-depth research on photon lantern devices and the continuous improvement of processing and manufacturing methods, self-matching photon lanterns can serve the generation of 1310nm and 1550nm high-order transverse mode lasers, and achieve the output of dozens or even hundreds of transverse modes.

[0071] By precisely controlling the parameters and arrangement of the fiber array and the taper ratio of the self-matching photonic lantern, efficient conversion of the 980 / 1310 / 1550nm three-band modes in the transition zone is achieved. The few-mode fiber port formed by the few-mode fiber and the taper can perform low-loss closed-loop transmission of multiple high-order transverse modes.

[0072] Using self-matching photon lanterns to build all-few-mode fiber ring cavity lasers to generate high-order transverse mode lasers corresponding to 1310nm and 1550nm can effectively simplify the laser structure and reduce dependence on other few-mode fiber devices. More importantly, the self-matching photon lanterns studied in this project have strong scalability and can be used to achieve the generation and conversion of multiple high-order modes, laying a key technical foundation for the efficient generation and flexible control of high-order transverse mode lasers.

[0073] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-band mode multiplexing self-matching photon lantern, characterized in that: include: The fiber array, transition zone, and few-mode port are connected in sequence; The optical fiber array is a portion in which a preset number of 980nm single-mode optical fibers with cladding, a 1310nm few-mode optical fiber with cladding, and a 1550nm few-mode optical fiber with cladding are placed in a quartz capillary, and the shape remains unchanged after adiabatic tapering to a preset stretching length according to a preset stretching ratio; The transition zone is a portion whose shape is changed after taper, and the few-mode port is a port portion whose shape is changed after taper; The stretching ratio is determined according to the normalized frequency of the few-mode optical fiber so that the few-mode port generates a linearly polarized LP mode, and the preset number corresponds to the number of modes applied by the photon lantern.

2. The three-band mode multiplexing self-matching photon lantern according to claim 1, characterized in that: The preset numbers include 3, 6, 10 and 15.

3. The three-band mode multiplexing self-matching photon lantern according to claim 1, characterized in that: The optical fiber arrangement before tapering is as follows: when the periphery of the few-mode optical fiber and the single-mode optical fiber overall array is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fiber are arranged at equal intervals.

4. The three-band mode multiplexing self-matching photon lantern according to claim 3, characterized in that: The LP modes are LP01 mode, LP11a mode and LP11b mode respectively. Accordingly, the preset number is 3. The optical fiber arrangement before tapering is a regular pentagonal arrangement of two adjacent few-mode optical fibers.

5. The three-band mode multiplexing self-matching photon lantern according to claim 4, characterized in that: The core and cladding refractive indices of the 980nm single-mode optical fiber are 1.45 and 1.444 respectively, the core and cladding refractive indices of the 1310nm few-mode optical fiber are 1.4685 and 1.444 respectively, the core and cladding refractive indices of the 1550nm few-mode optical fiber are 1.4669 and 1.444 respectively, and the refractive index of the quartz capillary is 1.

438.

6. The three-band mode multiplexing self-matching photon lantern according to claim 4, characterized in that: The core and cladding sizes of the two 980nm single-mode optical fibers are 4μm and 125μm respectively, the core and cladding sizes of the other 980nm single-mode optical fiber are 6μm and 125μm respectively, the core and cladding sizes of the 1310nm few-mode optical fiber are 15μm and 125μm respectively, and the core and cladding sizes of the 1550nm few-mode optical fiber are 15μm and 125μm respectively.

7. The three-band mode multiplexing self-matching photon lantern according to claim 4, characterized in that: The inner diameter of the quartz capillary is 400 μm, and the outer diameter is 415 μm.

8. A method for manufacturing a three-band mode multiplexing self-matching photon lantern, characterized in that: include: A preset number of 980 nm single-mode optical fibers including claddings, a 1550 nm few-mode optical fiber including claddings, and a 1310 nm few-mode optical fiber including claddings are placed in a quartz capillary; Adiabatically taper the quartz capillary tube with the built-in optical fiber to a preset stretching length according to a preset stretching ratio; Among them, the stretching ratio is determined according to the normalized frequency of the few-mode optical fiber so that the few-mode port generates an LP mode, and the few-mode port is the port part whose shape is changed after tapering, and the preset number corresponds to the number of modes applied by the photon lantern.

9. The method for manufacturing a three-band mode multiplexing self-matching photon lantern according to claim 8, characterized in that: The optical fiber arrangement before tapering is as follows: when the periphery of the few-mode optical fiber and the single-mode optical fiber overall array is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fiber are arranged at equal intervals.

10. A three-band mode multiplexing fiber laser, characterized in that: include: A 980nm laser and a three-band mode multiplexing self-matching photon lantern as described in any one of claims 1 to 7; The 980nm laser is connected to each 980nm single-mode optical fiber of the photon lantern, and the pump light injected from different 980nm single-mode optical fibers passes through the photon lantern to achieve selective excitation of the fundamental mode to a higher-order linear polarization mode; The 1310nm few-mode fiber and 1550nm few-mode fiber of the photon lantern are connected to the few ports through an optical switch to form a ring laser cavity. The few-mode erbium-doped fiber is connected to the ring laser cavity as a gain fiber to convert the wavelength running in the cavity to 1550nm or 1310nm.

Images