An amplified spontaneous emission light source

Abstract

The utility model discloses an embodiment of amplifying spontaneous emission light source. The amplifying spontaneous emission light source includes seed source and power amplifier, and the seed source is used for outputting the wide spectrum signal light of 900nm to 930nm wave band, and the power amplifier includes first doped neodymium optical fiber, first pump source and beam combiner, and the first pump source is used for outputting the first pump light, and the input end of beam combiner is connected with the output end of seed source and the output end of first pump source respectively, and the output end is connected with the input end of first doped neodymium optical fiber, and the first pump light is used for pumping neodymium ion in first doped neodymium optical fiber, so that neodymium ion is stimulated emission, and the seed signal light is amplified. The utility model solves the problem that the output power of the existing 900nm to 930nm wave band wide spectrum spontaneous emission light source is low, and it is difficult to fully meet the application requirement of high power nonlinear frequency multiplication, and realizes the stable output of high power amplifying spontaneous emission light with the center wavelength of 910-930nm.

Description

Technical Field

[0001] This utility model relates to amplified spontaneous emission light source technology, and more particularly to an amplified spontaneous emission light source. Background Technology

[0002] Amplified spontaneous emission (ASE) sources possess advantages such as stable output spectrum, wide wavelength range, moderate effective linewidth, strong resistance to environmental interference, high output power, and easy coupling with fiber optic systems. Therefore, they have become essential light sources for testing optical components (e.g., EDFA, fiber Bragg gratings) in wavelength division multiplexing (WDM) systems, signal processing, and medical optics. In particular, ASE sources based on neodymium-doped fiber in the 900nm band (0.9μm band) can generate blue light after frequency conversion, which has significant application value in underwater communication detection, laser display, and biomedicine.

[0003] While existing technologies can generate laser output in the 0.9μm band, there are few reports on the output characteristics of commercial neodymium-doped fiber and ASE light sources, making it difficult to meet the application needs of testing optical components in the 0.9μm band. Utility Model Content

[0004] This invention provides an amplified spontaneous emission light source to solve the problems of existing 900nm band amplified spontaneous emission light sources being difficult to implement and having low output power, thus meeting the application requirements of optical component testing and nonlinear frequency doubling.

[0005] This utility model embodiment provides an amplified spontaneous emission light source, including a seed source and a power amplifier; the seed source is used to output seed signal light in the 900nm to 930nm wavelength band; the power amplifier includes a first neodymium-doped fiber, a first pump source, and a combiner; the first pump source is used to output a first pump light; the input end of the combiner is connected to the output end of the seed source and the output end of the first pump source, respectively, and the output end is connected to the input end of the first neodymium-doped fiber; the first pump light is used to pump neodymium ions in the first neodymium-doped fiber to cause stimulated emission of neodymium ions and amplify the seed signal light.

[0006] Optionally, the seed source includes a second pump source, a second neodymium-doped fiber, a wavelength division multiplexer, and a broadband mirror; the second pump source is used to output the second pump light; the wavelength division multiplexer includes a pump input, a signal input, and an output; the pump input is connected to the output of the second pump source; the signal input is connected to the broadband mirror; the output of the wavelength division multiplexer is connected to the input of the second neodymium-doped fiber; the second pump light is injected into the second neodymium-doped fiber through the wavelength division multiplexer to pump neodymium ions and excite the neodymium ions to generate first amplified spontaneous emission. The signal light and the second amplified spontaneous emission signal light; wherein, the first amplified spontaneous emission signal light propagates toward the wavelength division multiplexer to the broadband reflector, and the second amplified spontaneous emission signal light propagates in the opposite direction to the first amplified spontaneous emission signal light; the broadband reflector is used to reflect the first amplified spontaneous emission signal light back to the second neodymium-doped fiber and suppress stray light in the amplified spontaneous emission signal light, so that the first amplified spontaneous emission signal light and the second amplified spontaneous emission signal light are bundled together in the second neodymium-doped fiber to form a seed signal light and output it.

[0007] Optionally, the broadband reflector includes a fiber optic coupler with a splitting ratio of 50:50. The input end of the fiber optic coupler is connected to the signal input end of the wavelength division multiplexer, and the two output ends of the fiber optic coupler are fused together to form a closed-loop structure.

[0008] Optionally, the seed source includes a first isolator; the input of the first isolator is connected to the output of the seed source, and the output is connected to the input of the bundle combiner; the first isolator is configured to allow light to propagate from the seed source toward the bundle combiner and to block light propagating in the opposite direction.

[0009] Optionally, the power amplifier also includes a second isolator; the input of the second isolator is connected to the output of the first neodymium-doped fiber; the second isolator is configured to allow light to propagate outward from the output of the first neodymium-doped fiber and block light propagating in the opposite direction from entering the first neodymium-doped fiber.

[0010] Optionally, the first neodymium-doped fiber is a double-clad neodymium-doped fiber; wherein the length of the double-clad neodymium-doped fiber is 6 to 10 meters; the cladding diameter of the double-clad neodymium-doped fiber is 70 to 90 μm, the cladding numerical aperture is optional, and the power amplifier also includes at least one section of matching fiber; one end of the matching fiber is connected to one end of the double-clad neodymium-doped fiber; the other end of the matching fiber is connected to an external optical device; the cladding diameter of the matching fiber is larger than the cladding diameter of the fiber of the external optical device, but smaller than the cladding diameter of the double-clad neodymium-doped fiber.

[0011] Optionally, the power amplifier also includes a cladding pump stripper; the input of the cladding pump stripper is connected to the output of the double-clad neodymium-doped fiber; the cladding pump stripper is used to strip residual pump light and stray light propagating in the cladding of the double-clad neodymium-doped fiber.

[0012] Optionally, the second neodymium-doped fiber is a single-mode neodymium-doped fiber; the length of the second neodymium-doped fiber is 0.5 to 1 m; the core diameter of the second neodymium-doped fiber is 2 to 4 μm, the numerical aperture is 0.16 to 0.36, and the absorption coefficient is greater than 120 dB / m.

[0013] Optionally, the pump wavelengths of the first and second pump lights are 808 nm.

[0014] This invention provides an amplified spontaneous emission light source. The amplified spontaneous emission light source includes a seed source and a power amplifier. The seed source outputs a seed signal light in the 900nm to 930nm wavelength band and serves as the dominant signal input to the power amplifier. The power amplifier includes a first neodymium-doped fiber, a first pump source, and a combiner. The first pump source outputs a first pump light as an excitation source; the input end of the combiner is connected to the output end of the seed source and the output end of the first pump source, and its output end is connected to the input end of the first neodymium-doped fiber; the first pump light is used to pump neodymium ions in the first neodymium-doped fiber to induce stimulated emission of the neodymium ions. The amplified spontaneous emission signal light input from the seed source acts as a "guide light," stimulating the stimulated emission process, causing the neodymium ions to synchronously release photons with the same frequency and phase as the input signal light, thereby amplifying the seed signal light. This invention solves the problem that the output power of existing 900nm to 930nm amplified spontaneous emission light sources is low and cannot fully meet the application requirements such as high-power nonlinear frequency doubling, and realizes stable output of high-power amplified spontaneous emission light with a center wavelength of 910-930nm. Attached Figure Description

[0015] Figure 1 A schematic diagram of an amplified spontaneous emission light source provided in an embodiment of this utility model;

[0016] Figure 2 The output spectrum of an amplified spontaneous emission light source is provided for an embodiment of this utility model. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0018] This embodiment of the invention provides an amplified spontaneous emission light source. Figure 1 This is a schematic diagram of the structure of an amplified spontaneous emission light source provided in an embodiment of the present invention. Figure 2 The output spectrum of an amplified spontaneous emission light source is provided for an embodiment of this utility model.

[0019] like Figure 1 As shown, the amplified spontaneous emission source includes: a seed source 10 and a power amplifier 20;

[0020] Seed source 10 is used to output amplified spontaneous emission signal light in the 900nm to 930nm band;

[0021] The power amplifier 20 includes: a first neodymium-doped fiber 21, a first pump source 22, and a bundler 23;

[0022] The first pump source is used to output the first pump light;

[0023] The output terminals of seed source 10 and first pump source 22 are respectively connected to the input terminal of bundle combiner 23;

[0024] The beam combiner 23 is used to couple the signal light output from the seed source 10 with the pump light output from the first pump source 22;

[0025] The output end of the combiner 23 is connected to the input end of the first neodymium-doped fiber 21;

[0026] The first pump light is used to pump neodymium ions in the first neodymium-doped fiber 21 to stimulate the neodymium ions to emit radiation and amplify the seed signal light.

[0027] The first pump light can be understood as a pump light within the neodymium ion absorption spectrum, specifically within the wavelength range of 790 nm to 820 nm.

[0028] Specifically, seed source 10 emits amplified spontaneous emission signal light in a specific 900nm to 930nm wavelength band. This signal light is a weak light signal excited by neodymium ions. Pump source emits pump light in the 800nm ​​wavelength band, such as 808nm. The combined light enters the first neodymium-doped fiber 21. The pump light is absorbed by the neodymium ions in the first neodymium-doped fiber 21, exciting the neodymium ions to a high energy level. When the excited neodymium ions encounter the seed signal light, stimulated emission occurs, releasing photons with the same wavelength, direction, and phase as the signal light, thereby amplifying the power of the original 900nm to 930nm wavelength band signal light.

[0029] In one specific embodiment, the first neodymium-doped fiber 21 is a double-layer neodymium-doped fiber comprising a core, an inner cladding, and an outer cladding. The core is composed of neodymium-doped ions (Nd). 3 The fiber core is composed of a silicon dioxide material with a +), used to conduct and amplify signal light in the 900nm band; the inner cladding is a pure silicon dioxide structure used to propagate pump light in the 800nm ​​band; the outer cladding uses a low refractive index material to form optical isolation with the inner cladding. The pump light is absorbed by neodymium ions in the fiber core as it travels back and forth multiple times within the inner cladding, achieving population inversion, and ultimately amplifying the spontaneous emission signal light propagating in the fiber core through stimulated emission.

[0030] During operation, the first neodymium-doped fiber 21 in the power amplifier 20 maintains a coaxial connection with the amplified spontaneous emission signal light output from the seed source 10. The amplified spontaneous emission signal light in the 900nm band output from the seed source 10 (mainly composed of 900-930nm wavelengths, containing a small amount of 1060nm stray light) is input to the power amplifier 20 as the dominant signal. Simultaneously, the pump light in the 800nm ​​band output from the first pump source 22 serves as the excitation source, and after being coupled with the dominant signal light through the combiner 23, they are injected together into the first neodymium-doped fiber 21. In the first neodymium-doped fiber 21, neodymium ions (Nd)... 3 The neodymium ion (Nd) absorbs 800 nm pump light and transitions from the ground state 4I9 / 2 to the excited state 4F5 / 2, followed by rapid nonradiative relaxation to the metastable state 4F3 / 2. The Nd ion is in the metastable state 4F3 / 2. 3 There are two main jump paths: 4 F3 / 2→ 4 I 11 / 2 (corresponding to ~1060nm) and 4F3 / 2 → 4 I9 / 2 (corresponding to ~900nm). The amplified spontaneous emission signal light in the 900nm to 930nm band input from seed source 10 serves as the "guide light," stimulating 4F3 / 2→ 4 The stimulated emission process of I9 / 2 allows neodymium ions to synchronously release photons with the same frequency and phase as the input signal light. This energy is coupled to the 900nm wavelength, effectively amplifying the signal light in that band while suppressing the spontaneous growth of stray light at 1060nm, thus achieving population inversion. The final output is as follows: Figure 2 The third power shown is an amplified spontaneous emission signal light with a center wavelength of 910-930nm.

[0031] This invention provides an amplified spontaneous emission light source. The amplified spontaneous emission light source includes a seed source and a power amplifier. The seed source outputs a seed signal light in the 900nm to 930nm wavelength band and serves as the dominant signal input to the power amplifier. The power amplifier includes a first neodymium-doped fiber, a first pump source, and a combiner. The first pump source outputs a first pump light as an excitation source; the input end of the combiner is connected to the output end of the seed source and the output end of the first pump source, and its output end is connected to the input end of the first neodymium-doped fiber; the first pump light is used to pump neodymium ions in the first neodymium-doped fiber to induce stimulated emission of the neodymium ions. The amplified spontaneous emission signal light input from the seed source acts as a "guide light," stimulating the stimulated emission process, causing the neodymium ions to synchronously release photons with the same frequency and phase as the input signal light, thereby amplifying the seed signal light. This invention solves the problem that the output power of existing 900nm to 930nm amplified spontaneous emission light sources is low and cannot fully meet the application requirements such as high-power nonlinear frequency doubling, and realizes stable output of high-power amplified spontaneous emission light with a center wavelength of 910-930nm.

[0032] In one specific embodiment, the first neodymium-doped fiber 21 is a double-clad neodymium-doped fiber with a length of 6 to 10 meters; the cladding diameter of the double-clad neodymium-doped fiber is 70 to 90 μm, the cladding numerical aperture is 0.36 to 0.56, the core diameter is 4 to 5 μm, the core numerical aperture is 0.13 to 0.19, and the absorption coefficient is less than 0.4 dB / m.

[0033] Preferably, the length of the first neodymium-doped fiber 21 is 8 meters. The cladding diameter of the first neodymium-doped fiber 21 is 80 μm, the cladding numerical aperture is 0.46, the core diameter is 4.5 μm, the core numerical aperture is 0.16, and the absorption coefficient is 0.4 dB / m. Neodymium ions exhibit relatively weak absorption in the 800 nm wavelength band, with an absorption coefficient of 0.4 dB / m. Therefore, a longer fiber is needed to provide more neodymium ions and a longer optical path, ensuring that the pump light is fully absorbed by the neodymium ions in the core during multiple reflections through the inner cladding. A trade-off is made between absorption efficiency and background losses, such as scattering and bending losses. 8 meters represents a compromise between ensuring high absorption and avoiding excessive losses / costs introduced by excessive length.

[0034] like Figure 1As shown, in an optional embodiment, the seed source 10 includes: a second pump source 11, a second neodymium-doped fiber 12, a wavelength division multiplexer 13, and a broadband mirror 14; the second pump source 11 is used to output a second pump light. The wavelength division multiplexer 13 includes a pump input terminal, a signal input terminal, and an output terminal. The pump input terminal is connected to the output terminal of the second pump source 11; the signal input terminal is connected to the broadband mirror 14; the output terminal of the wavelength division multiplexer 13 is connected to the input terminal of the second neodymium-doped fiber 12; the second pump light is injected into the second neodymium-doped fiber 12 through the wavelength division multiplexer 13 to pump neodymium ions and excite the neodymium ions to generate a first amplified spontaneous emission signal light and a second amplified spontaneous emission signal light.

[0035] The broadband reflector 14 is used to reflect the first amplified spontaneous emission signal light back to the second neodymium-doped fiber 12 and suppress stray light in the amplified spontaneous emission signal light, so that the first amplified spontaneous emission signal light and the second amplified spontaneous emission signal light are bundled together in the second neodymium-doped fiber 12 to form a seed signal light and output it.

[0036] The first amplified spontaneous emission signal light propagates towards the wavelength division multiplexer 13 and then to the broadband reflector 14. The second amplified spontaneous emission signal light propagates in the opposite direction to the first amplified spontaneous emission signal light. The second and first amplified spontaneous emission signal lights can be understood as spontaneously emitted signal lights generated in the second neodymium-doped fiber 12 and propagating spontaneously in the output direction and the reverse output direction, respectively. The second neodymium-doped fiber 12 can be understood as an optical fiber with neodymium ions in its core that allows only the fundamental mode light to propagate. The broadband reflector 14 can be understood as an optical filter with wavelength-selective reflection function, exhibiting high reflectivity for signal light in the 900nm band and high transmittance for signal light in the 1060nm band. The second pump source 11 can be understood as a light source device used to provide pump light in the 800nm ​​band, such as 808nm, to drive the seed source 10. For example, the second pump source 11 can be a single-mode pump source, such as a single-mode pumped laser diode.

[0037] Specifically, during operation, the second pump source 11 outputs 800nm ​​pump light, and the forward-propagating amplified spontaneous emission light enters the second Nd:12 fiber 12 via the output of the wavelength division multiplexer 13. In the second Nd:12 fiber 12, after absorbing the 800nm ​​pump light, Nd:1 ions transition from the ground state 4I9 / 2 to the excited state 4F5 / 2, and then undergo non-radiative relaxation to become the metastable state 4F3 / 2. The Nd:1 ions in the metastable state 4F3 / 2... 3 There are two main jump paths: 4 F3 / 2→ 4 I 11 / 2 (corresponding to ~1060nm) and 4F3 / 2 → 4I9 / 2 (corresponding to ~900nm). The excitation light generated by the transition is continuously reflected in the second Nd:12 fiber. Eventually, a portion of the forward-propagating light, i.e., the first amplified spontaneous emission signal light, is output from the output end of the second Nd:12 fiber. The other portion, the reverse-propagating light, i.e., the second amplified spontaneous emission signal light, is reflected by the broadband mirror 14. During the reflection process, the 900nm signal light is reflected by the broadband mirror 14, while the 1060nm stray light escapes from the system. The reflected signal light mainly consists of 900-930nm wavelength signal light and a small amount of 1060nm stray light. Due to the guiding effect of stimulated emission, the 900-930nm wavelength signal light acts as a "guide light," stimulating the 4F3 / 2→ 4 The stimulated emission process of I9 / 2 allows neodymium ions to simultaneously release photons of the same frequency and phase as the input signal light, thereby generating more light in the 900nm band and suppressing the spontaneous growth of stray light in the 1060nm band. Ultimately, seed source 10 outputs amplified spontaneous emission light dominated by the 900nm band.

[0038] In one specific embodiment, the second neodymium-doped fiber 12 is a single-mode neodymium-doped fiber; the length of the second neodymium-doped fiber 12 is 0.5 to 1 m; the core diameter of the second neodymium-doped fiber 12 is 2 to 4 μm, the numerical aperture is 0.16 to 0.36, and the absorption coefficient is greater than 120 dB / m.

[0039] Preferably, the length of the second neodymium-doped fiber 12 is 0.75m; the core diameter of the second neodymium-doped fiber 12 is 3μm, the numerical aperture is 0.26, and the absorption coefficient is 150dB / m.

[0040] Specifically, an absorption coefficient of 150 dB / m ensures high absorption of pump light by the fiber, while short fiber lengths (e.g., 0.75 m) reduce background loss caused by scattering and bending. A core diameter of 3 μm and a numerical aperture of 0.26 ensure that the output is near-diffraction-limited single-mode amplified spontaneous emission light, laying the foundation for a high-quality input signal for subsequent power amplifiers.

[0041] In one specific embodiment, when the 808nm pump power remains constant at 1.25W, the output power of the 900nm amplified spontaneous emission signal light output by amplifier 20 increases with the increase of the length of the first neodymium-doped fiber 21. When the length of the first neodymium-doped fiber 21 is 8m, the final output power is 25mW. The signal light spectrum of this light source is as follows: Figure 2 As shown, the center wavelength is 921.5nm, and the 10dB bandwidth is approximately 20nm.

[0042] In one specific embodiment, the pump wavelengths of the first pump light and the second pump light are 790 nm to 810 nm.

[0043] Specifically, a pump light with a preferred pump wavelength of 808 nm is preferred, as 808 nm is located in the neodymium ion (Nd) wavelength range. 3 +) The strongest absorption peak (800-810nm) in silicon-based optical fiber ensures that the pump light energy is efficiently absorbed by neodymium ions in the fiber core.

[0044] In an optional embodiment, the broadband reflector 14 includes an optical fiber coupler with a splitting ratio of 1:1. The input end of the optical fiber coupler is connected to the signal input end of the wavelength division multiplexer 13, and the two output ends of the optical fiber coupler are fused together to form a closed-loop structure.

[0045] Specifically, during operation, the reverse-amplified spontaneous emission signal light enters the fiber coupler with a splitting ratio of 1:1 from the signal input end of the wavelength division multiplexer 13. After being split into two beams, they enter the closed-loop structure formed by fusion splicing from the two output ends respectively. The two beams after splitting propagate in opposite directions within the loop and re-converge.

[0046] It should be noted that by setting a reasonable closed-loop length, the two 900nm beams satisfy the constructive interference condition, thus superimposing in phase at the coupler entrance and reflecting back to the original path. Simultaneously, the two 1060nm beams must satisfy the destructive interference condition, thus canceling each other out of phase at the coupler. Finally, the amplified 900nm spontaneous emission light is output through wavelength division multiplexer 13, while the 1060nm light energy is emitted laterally from the closed loop.

[0047] For example, when the optical path difference of a 900nm signal light in a fiber optic coupler with a splitting ratio of 1:1 is an even multiple of half a wavelength, coherent superposition doubles the photon density, thereby increasing the probability of stimulated emission. In contrast, the optical path difference of a 1060nm signal light is an odd multiple of half a wavelength, resulting in destructive interference radiation.

[0048] In an optional embodiment, the power amplifier 20 further includes at least one section of matching optical fiber;

[0049] One end of the matching fiber is connected to one end of the double-clad neodymium-doped fiber;

[0050] The other end of the matching optical fiber is connected to external optical devices;

[0051] The cladding diameter of the matching fiber is larger than that of the fiber of the external optical device, but smaller than that of the double-clad neodymium-doped fiber.

[0052] Specifically, the industry standard cladding diameter for existing standard optical fibers is 125 μm, while the diameter of the double-clad neodymium-doped fiber used in this application is 80 μm. The cross-sectional area ratio between the 125 μm cladding diameter fiber and the 80 μm cladding diameter fiber is approximately 2.44. Direct fusion splicing would cause scattering of pump light or signal light at the splice interface. Using matched fibers to achieve a gradual change in cladding diameter can effectively reduce cladding mode loss.

[0053] For example, directly fusion splicing 80μm and 125μm optical fibers results in a cladding mode loss >3dB. When using a matching fiber, the fusion loss between the 80μm fiber and the matching fiber is approximately 0.3dB, and the fusion loss between the matching fiber and the 125μm fiber is approximately 0.5dB. Ultimately, the loss can be reduced to 0.5dB + 0.3dB = 0.8dB.

[0054] In an optional embodiment, seed source 10 further includes a first isolator 15;

[0055] The input terminal of the first isolator 15 is connected to the output terminal of the seed source 10, and the output terminal is connected to the input terminal of the bundle combiner 23.

[0056] The first isolator 15 is configured to allow light to propagate from the seed source 10 toward the bundler 23 and to block light propagating in the opposite direction.

[0057] Specifically, the first isolator 15 is positioned between the output end of the seed source and the combiner 23 to block spontaneously radiating back-propagating light that may be generated by the double-clad fiber of the power amplifier from entering the seed source, thereby avoiding output power fluctuations and loss of control over 1060nm stray light gain caused by the back light disturbance causing population inversion within the seed source.

[0058] In an optional embodiment, the power amplifier 20 further includes a second isolator 24;

[0059] The input of the second isolator 24 is connected to the output of the first neodymium-doped fiber 21;

[0060] The second isolator 24 is configured to allow light to propagate outward from the output end of the first neodymium-doped fiber 21 and block light propagating in the opposite direction from entering the first neodymium-doped fiber 21.

[0061] Specifically, the second isolator 24 is located at the output of the power amplifier 24 to prevent external reflected light from returning to the amplifier, thereby eliminating the risk of self-excited oscillation and damage to optical devices caused by the secondary amplification of reflected light in the amplifier.

[0062] In an optional embodiment, the power amplifier 20 further includes a cladding pump stripper 25;

[0063] The input end of the cladding pump stripper 25 is connected to the output end of the double-clad neodymium-doped fiber;

[0064] The cladding pump stripper 25 is used to strip residual pump light and stray light propagating in the cladding of a double-clad neodymium-doped fiber.

[0065] The cladding pump stripper 25 can be understood as an optical structure that selectively strips residual pump light and stray light propagating in the inner cladding of an optical fiber while retaining the effective signal light in the fiber core. The residual pump light can be understood as the remaining optical power in the pump light that is not absorbed by neodymium ions in the double-clad neodymium-doped fiber and continues to propagate in the optical path. The stray light can be understood as the undesired light generated by non-target energy level transitions of neodymium ions or stray radiation in the optical path, in addition to the target 900nm amplified spontaneous emission light and the 800nm ​​pump light. For example, the main stray light is the 1060nm signal light.

[0066] Specifically, the cladding pump stripper 25 is used to convert the stripped light energy into heat and discharge it through the heat dissipation structure to prevent energy accumulation from causing local high temperatures.

[0067] It should be noted that, regarding the placement of the cladding pump stripper 25, if it is positioned before the second isolator 24, stray cladding light will be stripped first, and the isolator will only process the pure fiber core signal. Conversely, if the cladding pump stripper 25 is positioned after the second isolator 24, some residual pump light will be absorbed by the isolator, which may easily cause the isolator to overheat and be damaged.

[0068] For example, the cladding pump stripper 25 can use a high-refractive-index adhesive layer to disrupt the total internal reflection condition of the cladding to strip the cladding light.

Claims

1. A light source for amplifying spontaneous emission, characterized in that, Includes a seed source (10) and a power amplifier (20); The seed source (10) is used to output seed signal light in the 900nm to 930nm band; The power amplifier (20) includes a first neodymium-doped fiber (21), a first pump source (22), and a combiner (23). The first pump source (22) is used to output the first pump light; The input end of the combiner (23) is connected to the output end of the seed source (10) and the output end of the first pump source (22), respectively, and the output end is connected to the input end of the first neodymium-doped fiber (21); The first pump light is used to pump neodymium ions in the first neodymium-doped fiber (21) to stimulate the neodymium ions to emit radiation and amplify the seed signal light.

2. The amplified spontaneous emission light source according to claim 1, characterized in that, The seed source (10) includes a second pump source (11), a second neodymium-doped fiber (12), a wavelength division multiplexer (13), and a broadband reflector (14). The second pump source (11) is used to output the second pump light; The wavelength division multiplexer (13) includes a pump input, a signal input, and an output; the pump input is connected to the output of the second pump source (11); the signal input is connected to the broadband mirror (14); and the output of the wavelength division multiplexer (13) is connected to the input of the second neodymium-doped fiber (12). The second pump light is injected into the second neodymium-doped fiber (12) through a wavelength division multiplexer (13) to pump neodymium ions and excite the neodymium ions to generate a first amplified spontaneous emission signal light and a second amplified spontaneous emission signal light; wherein, the first amplified spontaneous emission signal light propagates toward the wavelength division multiplexer (13) to the broadband reflector (14), and the second amplified spontaneous emission signal light propagates in the opposite direction to the first amplified spontaneous emission signal light; The broadband reflector (14) is used to reflect the first amplified spontaneous emission signal light back to the second neodymium-doped fiber (12) and suppress stray light in the amplified spontaneous emission signal light, so that the first amplified spontaneous emission signal light and the second amplified spontaneous emission signal light are bundled together in the second neodymium-doped fiber (12) to form the seed signal light and output it.

3. The amplified spontaneous emission light source according to claim 2, characterized in that, The broadband reflector (14) includes an optical fiber coupler with a splitting ratio of 50:

50. The input end of the optical fiber coupler is connected to the signal input end of the wavelength division multiplexer (13), and the two output ends of the optical fiber coupler are fused together to form a closed-loop structure.

4. The amplified spontaneous emission light source according to claim 1, characterized in that, The seed source (10) includes a first isolator (15); The input of the first isolator (15) is connected to the output of the seed source (10), and the output is connected to the input of the bundle combiner (23); The first isolator (15) is configured to allow light to propagate from the seed source (10) toward the combiner (23) and block light propagating in the opposite direction.

5. The amplified spontaneous emission light source according to claim 1, characterized in that, The power amplifier (20) also includes a second isolator (24); The input end of the second isolator (24) is connected to the output end of the first neodymium-doped fiber (21); The second isolator (24) is configured to allow light to propagate outward from the output end of the first neodymium-doped fiber (21) and block light propagating in the opposite direction from entering the first neodymium-doped fiber (21).

6. The amplified spontaneous emission light source according to claim 1, characterized in that, The first neodymium-doped fiber (21) is a double-clad neodymium-doped fiber; The length of the double-clad neodymium-doped fiber is 6-10 meters; the cladding diameter of the double-clad neodymium-doped fiber is 70-90 μm, the cladding numerical aperture is 0.36-0.56, the core diameter is 4-5 μm, the core numerical aperture is 0.13-0.19, and the cladding absorption coefficient is less than 0.4 dB / m@800 nm.

7. The amplified spontaneous emission light source according to claim 6, characterized in that, The power amplifier (20) also includes at least one section of matching optical fiber; One end of the matching optical fiber is connected to one end of the double-clad neodymium-doped optical fiber; The other end of the matching optical fiber is connected to an external optical device; The cladding diameter of the matching fiber is larger than the cladding diameter of the external optical device fiber, but smaller than the cladding diameter of the double-clad neodymium-doped fiber.

8. The amplified spontaneous emission light source according to claim 6, characterized in that, The power amplifier (20) also includes a cladding pump stripper (25). The input end of the cladding pump stripper (25) is connected to the output end of the double-clad neodymium-doped fiber; The cladding pump stripper (25) is used to strip residual pump light and stray light propagating in the cladding of the double-clad neodymium-doped fiber.

9. The amplified spontaneous emission light source according to claim 2, characterized in that, The second neodymium-doped fiber (12) is a single-mode neodymium-doped fiber; the length of the second neodymium-doped fiber (12) is 0.5~1m; the core diameter of the second neodymium-doped fiber (12) is 2~4μm, the numerical aperture is 0.16~0.36, and the absorption coefficient is greater than 120dB / m@800nm.

10. The amplified spontaneous emission light source according to claim 2, characterized in that, The pump wavelengths of the first pump light and the second pump light are 808 nm.

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