Triple-band mode multiplexing self-matching photon lantern and manufacturing method

Abstract

The present invention provides a three-band mode multiplexing self-matching photon lantern and its manufacturing method, belonging to the field of optical communications. The photon lantern comprises: a fiber array, a transition region, and a few-mode port connected in sequence. The fiber array comprises a predetermined number of 980nm single-mode fibers with cladding, a single 1310nm few-mode fiber with cladding, and a single 1550nm few-mode fiber with cladding, placed in a quartz capillary tube. The fiber array is the portion that remains unchanged after adiabatically tapering to a predetermined length according to a predetermined stretch ratio. The transition region is the portion that changes shape after tapering, and the few-mode port is the port portion that changes shape after tapering. The photon lantern can achieve selective mode conversion at the 980nm wavelength, maintain the 1550nm and 1310nm wavelength modes, and transmit low-loss closed-loop signals. It can be used to construct a fiber ring laser cavity, enabling direct oscillation and output of multiple high-order modes within the all-few-mode fiber ring laser cavity, thus avoiding single-mode and few-mode incompatibility issues.

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] Currently, communication systems based on single-mode fiber are approaching their transmission capacity limits, unable to meet the demands of economic and social development. High-order transverse modes in optical fiber possess orthogonality, unique spatial intensity, and polarization distribution characteristics. Through mode division multiplexing, they can expand the spatial dimension of information transmission, breaking through the transmission capacity bottleneck of existing single-mode fiber communication systems and fully meeting the rapidly growing bandwidth demands of 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 commonly 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 are crucial for communication quality and bandwidth. Among the aforementioned mode conversion devices, the mode-selective photon lantern is an ideal mode conversion device. However, its use in fiber laser systems presents incompatibility issues between single-mode and few-mode. Summary of the Invention

[0005] In response to 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 region, 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 portion remains unchanged after adiabatically tapering to a preset stretched length according to a preset stretching ratio; the transition region 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 fibers so that the few-mode port generates a linearly polarized LP mode, and the preset number corresponds to the number of modes used in the photon lantern.

[0007] According to a three-band mode multiplexing self-matching photonic lantern provided by the present invention, the preset numbers include 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. 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.

[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 the 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 according to 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 changes after tapering, and the preset number corresponds to the number of modes applied by 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 the present invention, a method for manufacturing a three-band mode multiplexing self-matching photon lantern is provided, wherein 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 above-mentioned three-band mode multiplexing self-matching photon lanterns; 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 fiber to convert the wavelength operating in the cavity to 1550nm or 1310nm.

[0017] The three-band mode multiplexing self-matching photon lantern and its manufacturing method provided by the present invention can realize 980 / 1550 / 1310nm three-band mode multiplexing, that is, selective conversion of the 980nm wavelength mode, maintenance of the 1550nm and 1310nm wavelength modes, and low-loss closed-loop transmission. It can be used to construct a full multimode (few-mode) fiber ring laser cavity, 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 generation of high-order mode outputs 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

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

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

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

[0022] Figure 4 Schematic diagram of the simulation results of mode field evolution corresponding to different taper ratios of the novel three-mode selective self-matching photon lantern for 980nm laser transmission provided by the present invention;

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

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

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

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

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

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

[0029] Figure 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] Figure 12 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] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described 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 making creative efforts shall fall within the scope of protection of the present invention.

[0033] This invention provides a novel photon lantern device and fabrication method, designed to address the incompatibility issues between single-mode and multimode systems associated with direct use of photon lanterns in fiber lasers. By designing a novel photon lantern, it can be fully integrated into the construction of a fully few-mode fiber ring laser, both structurally and functionally, simplifying the system architecture and improving mode conversion efficiency.

[0034] Its 980 / 1310 / 1550nm three-band mode multiplexing characteristics make it suitable for building fiber lasers, eliminating the need for wavelength division multiplexers. In addition, its matching characteristics between the input 1550nm few-mode fiber or 1310nm few-mode fiber and the output (multimode) few-mode port can be used to construct an all-few-mode fiber ring laser cavity, achieving direct oscillation and output of multiple high-order mode lasers within the all-few-mode fiber ring laser cavity.

[0035] The following combination Figures 1-12 The present invention describes a three-band mode multiplexing self-matching photon lantern and a manufacturing method thereof. Figure 1 This is a 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 region 2, and a few-mode port 3 connected in sequence; the optical fiber array 1 is a portion of a preset number of 980nm single-mode optical fibers 1-1 containing cladding, a 1310nm few-mode optical fiber 1-2 containing cladding, and a 1550nm few-mode optical fiber 1-3 containing cladding placed in a quartz capillary, and the shape remains unchanged after adiabatically tapering to a preset stretched length according to a preset stretching ratio; the transition region 2 is the portion whose shape changes after tapering, and the few-mode port 3 is the port portion whose shape changes after tapering; wherein the stretching ratio is determined according to the normalized frequency of the few-mode optical fibers so that the few-mode port generates a linearly polarized LP mode, and the preset number corresponds to the number of modes used in the photon lantern.

[0036] Fiber array 1 is placed in a specific arrangement within a low-refractive-index quartz sleeve and tapered via adiabatic fusion to form transition zone 2. During the adiabatic tapering process, fiber array 1 gradually fuses together, with the 980nm single-mode fiber core, 1310nm few-mode fiber, and 1550nm few-mode fiber core gradually becoming thinner until they lose their ability to bind light. The original cladding within fiber array 1 becomes the new core, and the surrounding low-refractive-index quartz sleeve becomes the new cladding. When the tapering reaches a predetermined length based on a preset tapering ratio, tapering is stopped, ultimately forming a new few-mode waveguide with parameters similar to those of the 1310nm and 1550nm few-mode fibers, supporting closed-loop, low-loss transmission.

[0037] The adiabatic tapered few-mode port 3 is compatible with the 1310nm few-mode fiber 1-2 and the 1550nm few-mode fiber 1-3, enabling transmission in the same mode. Light with a wavelength of 980nm is injected from different fibers within the 980nm single-mode fiber cluster 1-1. After passing through the novel photon lantern, the 980nm lightwave is converted from the fundamental mode to a specific mode. Light with a wavelength of 1310nm is injected from the 1310nm few-mode fiber 1-2 and evolves through the novel photon lantern, achieving mode morphology preservation and low-loss transmission. The 1310nm few-mode fiber 1-2 is compatible with the few-mode port 3. Light with a wavelength of 1550nm is injected from the 1550nm few-mode fiber 1-3 and evolves through the novel photon lantern, achieving mode morphology preservation and low-loss transmission. The 1550nm few-mode fiber 1-3 is compatible 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, selective conversion of the 980nm wavelength mode, maintenance of the 1550nm and 1310nm wavelength modes, and low-loss closed-loop transmission. It can be used to construct a full multimode (few-mode) fiber ring laser cavity, 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 generation of high-order mode outputs 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 production cost, simple use process, and mode conversion efficiency much higher than other devices. It can also achieve low-loss insertion in the laser system, making it suitable for large-scale promotion and use and 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 fibers and the single-mode optical fibers is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fibers are arranged at equal intervals.

[0042] When the embodiment of the present invention is arranged, the outer periphery of the optical fiber array is equally spaced and has a regular polygonal structure, 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] The schematic diagram of the new self-matching photon lantern with three-mode selectivity is shown in the figure. Figure 1 As shown. The few-mode port can selectively excite 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 research conclusions on the influence of optical fiber geometric arrangement on mode conversion in photon lanterns, it is necessary to support LP mn For photon lanterns that propagate and convert modes (m is the radial order of the mode field, n is the angular order of the mode field), the fiber array should be arranged in the form of m concentric circles. The number of fibers on each ring should be N = 2n max +1, thus 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 part of the new photon lantern, but it itself does not inject 980nm light beam, therefore, the five optical fibers are arranged according to a regular pentagon, and the two few-mode optical fibers are arranged adjacent to each other, to ensure the selective excitation of the modes in the photon lantern while also 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 4 μm and 125 μm, respectively; the core and cladding sizes of another 980nm single-mode optical fiber are 6 μm and 125 μm, respectively; the core and cladding sizes of the 1310nm few-mode optical fiber are 15 μm and 125 μm, respectively; and the core and cladding sizes of the 1550nm few-mode optical fiber are 15 μm and 125 μm, 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 new self-matching photon lantern with three modes of selectivity, the preset parameters of the three 980nm single-mode optical fibers need to be designed differently according to the transmission characteristics of the modes. The embodiment of the present invention adopts a preferred solution with better performance, and the core and cladding refractive indices of the three 980nm single-mode optical fibers in the new self-matching photon lantern with three modes of selectivity are designed to be 1.45 and 1.444 respectively. The core and cladding sizes of the two 980nm single-mode optical fibers are designed to be 4μm and 125μm respectively, which can selectively stimulate LP. 11a and LP 11b mode, and the core and cladding sizes of another 980nm single-mode fiber are designed to be 6μm and 125μm, respectively, to stimulate LP 01 The core and cladding refractive indices of the 1310nm three-mode 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 indices of the 1550nm three-mode 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-mentioned optical fiber and cladding dimensions are not conventional choices in the art, but are dimension parameters with better coupling effects set to better match the regular pentagonal arrangement of the five optical fibers in the above-mentioned embodiment.

[0052] When the claddings of the 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 stretch ratio is 0.1.

[0054] According to the above parameters, the simulation settings of the new three-mode selective self-matching photon lantern are carried out to simulate the light field evolution process of the 980nm light wave inside the new three-mode selective self-matching photon lantern. Figure 2 Schematic diagram of the new self-matching photon lantern with three-mode selectivity for 980nm laser transmission. The highlighted parts are the cores of 980nm single-mode optical fibers 100, 101, and 102. The cores of 100 and 101 have the same size (4μm), corresponding to the excitation of 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 the 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 settings of the new three-mode selective self-matching photon lantern are 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 of 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 settings of the new three-mode selective self-matching photon lantern are 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 of 1310nm laser transmission. The highlighted part is the 1310nm few-mode fiber core after tapering. Figure 9 The study demonstrates how the effective refractive index of the 1310nm mode varies with the taper ratio. When the taper ratio is greater than 0.3, the 1310nm tri-mode fiber can stably transmit both the LP01 and LP11 modes. As the taper ratio decreases, the LP11 mode leaks into the cladding first. When the taper ratio drops below 0.1, the core can no longer guide the mode, and the fiber array's cladding becomes the new "core," guiding the mode for stable transmission. Figure 10 In the experiment, when the tapering ratio reaches 0.05, the LP01, LP11a and LP11b modes injected into the original 1310nm three-mode 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 three-mode selective self-matching photonic lantern, and low-loss closed-loop transmission can be achieved when connected to the few-mode fiber.

[0057] The new photon lantern can solve the incompatibility problem between single-mode and few-mode that exists 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. When used to construct fiber lasers, it can get rid of the dependence on wavelength division multiplexing devices. The new photon lantern can be used to construct an all-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 a 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] Figure 11 This is a flow chart of the method for manufacturing a three-band mode multiplexing self-matching photon lantern provided by the present invention, as shown in FIG. Figure 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 including claddings, a 1550 nm few-mode optical fiber including claddings, and a 1310 nm few-mode optical fiber including claddings in a quartz capillary tube;

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

[0062] The stretching ratio is determined according to the normalized frequency of the few-mode fiber so that the few-mode port generates an LP mode. The few-mode port is the port portion whose shape changes after tapering. 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 fibers and the single-mode optical fibers is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fibers are arranged at equal intervals.

[0064] In one embodiment, the LP modes are LP01, LP11a, and LP11b, respectively. Accordingly, the preset number is three, and the fiber arrangement before tapering is a regular pentagonal arrangement of two adjacent few-mode fibers. The method embodiments provided in the present invention are intended to implement the aforementioned device embodiments. For specific processes and details, please refer to the aforementioned device embodiments and 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 content in the aforementioned three-band mode multiplexing self-matching photon lantern embodiment.

[0066] Figure 12 Schematic diagram of the structure of the three-band mode multiplexing fiber laser provided by the present invention, such as Figure 12 As shown, the three-band mode multiplexing fiber laser includes: a 980nm laser and any 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 fiber and the 1550nm few-mode 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 fiber is connected to the ring laser cavity as a gain fiber to convert the wavelength operating in the cavity to 1550nm or 1310nm.

[0067] Taking the novel three-mode selective self-matching photon lantern as an example, it can be used to construct an all-few-mode fiber ring cavity continuous light laser, achieving 1550nm and 1310nm high-order mode laser output. Specifically, the novel photon lantern's 980nm single-mode fiber cluster can be connected to the 980nm laser via an optical switch. Pump light injected from different fibers within the 980nm single-mode fiber cluster passes through the novel photon lantern, achieving selective excitation of the fundamental mode to specific high-order modes. The novel photon lantern's 1550nm few-mode fiber and 1310nm few-mode fiber are connected to the few-mode port via an optical switch to form a ring laser cavity. The output wavelength can be selected to be 1310nm or 1550nm based on the wavelength of the signal light input into the ring cavity. A few-mode erbium-doped fiber is introduced into the ring cavity as a gain fiber, converting the wavelength operating within 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 light transmission, and a polarization controller is used to adjust the polarization state of the mode field to 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. An optical 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, by adding two few-mode fibers to the lantern's fiber array, the present invention constructs a self-matching photon lantern capable of lasing multiple high-order transverse modes at 1310 / 1550nm. This self-matching photon lantern enables three-band mode multiplexing at 980 / 1310 / 1550nm. 980nm pump light input through different single-mode fibers is selectively converted into corresponding high-order transverse modes. The self-cavity properties of the few-mode fibers enable low-loss closed-loop transmission of the 1310nm and 1550nm high-order transverse modes.

[0070] The present invention's research on self-matching photonic lanterns has enriched the types and functions of photonic lanterns. As the research on photonic lantern devices deepens and the processing and manufacturing methods continue to improve, self-matching photonic lanterns can serve the generation of 1310nm and 1550nm high-order transverse mode lasers, achieving the output of dozens or even hundreds of transverse modes.

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

[0072] Using a self-matching photonic lantern to construct an all-few-mode fiber ring laser, generating high-order transverse modes at 1310nm and 1550nm, effectively simplifies the laser structure and reduces reliance on other few-mode fiber components. Importantly, the self-matching photonic lantern studied in this project is highly scalable and can be used to generate and convert 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. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[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 various 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 claddings, one 1310nm few-mode optical fiber with claddings, and one 1550nm few-mode optical fiber with claddings are placed in a quartz capillary tube and a shape remains unchanged after adiabatically tapering to a preset stretched length according to a preset stretching ratio; The transition zone is the portion whose shape changes after taper, and the few-mode port is the port portion whose shape changes after taper; wherein the stretching ratio is determined according to the normalized frequency of the few-mode 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; The optical fiber arrangement before tapering is as follows: when the periphery of the overall array of the few-mode optical fibers and the single-mode optical fibers is arranged in a regular polygon, adjacent optical fibers in the single-mode optical fibers are arranged at equal intervals.

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 2, 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.

4. The three-band mode multiplexing self-matching photon lantern according to claim 1, 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.

5. The three-band mode multiplexing self-matching photon lantern according to claim 3, 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.

6. The three-band mode multiplexing self-matching photon lantern according to claim 3, characterized in that: The inner diameter of the quartz capillary is 400 μm, and the outer diameter is 415 μm.

7. 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 containing claddings, a 1550 nm few-mode optical fiber containing claddings, and a 1310 nm few-mode optical fiber containing claddings are placed in a quartz capillary tube; Adiabatically tapering the quartz capillary tube containing the built-in optical fiber to a preset stretching length according to a preset stretching ratio; In which, 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. The few-mode port is the port part whose shape changes after tapering. The preset number corresponds to the number of modes applied by the photon lantern. The optical fiber arrangement before tapering is: 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.

8. A three-band mode multiplexing fiber laser, characterized in that: include: A 980nm laser and a three-band mode multiplexing self-matching photon lantern according to any one of claims 1 to 6; 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 the higher-order linear polarization mode; The 1310nm few-mode fiber and 1550nm few-mode fiber of the photon lantern are connected to the few-mode port 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.

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