CN114430139A - Polarization-maintaining single-frequency broadening and amplifying system - Google Patents
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06754—Fibre amplifiers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/09408—Pump redundancy
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- H—ELECTRICITY
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/10061—Polarization control
Abstract
A polarization-maintaining single-frequency broadening amplifying system uses a polarization-controlling single-frequency broadening fiber amplifier system based on a white noise source phase modulation technique. The stimulated Brillouin scattering and the stimulated Raman scattering are effectively inhibited, the nonlinear threshold is improved, and the manufacturing cost is reduced. Finally, the amplification output of the linearly polarized 3kW narrow linewidth fiber laser is successfully realized. The light-light conversion efficiency is 78%, the beam quality M2 of the final output laser is approximately equal to 1.2, and the polarization extinction ratio is 15 dB.
Description
Technical Field
The invention relates to a polarization-maintaining single-frequency broadening amplifying system, in particular to a polarization-controlling single-frequency broadening optical fiber amplifying system utilizing a white noise phase modulation technology.
Background
The high-power narrow-linewidth optical fiber laser has the outstanding advantages of good beam quality, high efficiency, compact structure, good coherence and the like, and is generally applied to the fields of beam synthesis, earth detection, scientific research and the like. And coherent and spectral combining are efficient solutions to achieve higher power output while maintaining good beam quality. The coherent combination/spectrum combination system requires a single optical fiber laser narrow linewidth output of a basic unit module. The mode instability effect and the nonlinear effect are two major bottleneck scientific problems limiting the power improvement of the high-power narrow-linewidth optical fiber laser, particularly the mode instability effect of the large-mode-field optical fiber, not only can the power improvement be severely limited, but also the beam quality of the output laser can be rapidly degraded, and the mode instability effect and the nonlinear effect are the technical problems to be solved urgently in the development of the high-power optical fiber laser. In response, domestic and foreign scholars propose various technical schemes such as pulse pumping, dynamic mode excitation, multi-core fiber and the like to relieve the mode instability effect.
At present, the single-frequency broadening amplifier system has the following schemes: (1) the single-cavity 3000W optical fiber laser has the advantages of high integration level, easiness in implementation and low cost; but the final output laser is randomly polarized, the spectral width is wider, generally greater than about 6nm, and the beam quality is poor, M2 is approximately equal to 1.3. And (2) the non-polarization-maintaining single-frequency broadening amplifying system can realize relatively good beam quality, such as M2 ≈ 1.2, and the spectral linewidth is relatively narrow, usually about 30GHz, but the final output laser is randomly polarized and has poor stability. (3) The full polarization maintaining single-frequency broadening and amplifying system based on the white noise source phase modulation technology has the advantages that the beam quality is relatively better, M2 is approximately equal to 1.2, the spectral line width is relatively narrow, generally about 30GHz, the final output laser is linear polarization, but the device parameter requirement is high, the realization difficulty is high, and the cost is high. In recent technological developments, the possibility of making a polarization-controlled single-frequency broadening amplification system using white noise source phase modulation techniques is revealed, which theoretically enables line-polarized output oscillation with higher beam quality and narrower spectral line width. Meanwhile, a nonlinear threshold value is improved, the manufacturing difficulty and the cost are reduced, but the realization difficulty is higher based on the current theory, few documents relate to how to manufacture an amplification system which is easy to realize, and meanwhile, no document discloses how to reasonably design the device structure layout and the parameters of the polarization control single-frequency broadening amplification system so as to realize extremely polarization-preserving single-frequency broadening amplification.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a polarization-maintaining single-frequency broadening and amplifying system which overcomes the defects of the prior art and has reasonable design.
The phase modulation technology based on the white noise source is used for effectively inhibiting stimulated Brillouin scattering and stimulated Raman scattering, and the single-frequency broadening and amplifying system adopting the polarization control technology improves the nonlinear threshold value and reduces the manufacturing cost. Finally, the amplification output of the linearly polarized 3kW narrow linewidth fiber laser is successfully realized. The light-light conversion efficiency is 78%, the beam quality M2 of the final output laser is approximately equal to 1.2, and the polarization extinction ratio is 15 dB.
In order to achieve the purpose, the invention is realized by the following technical scheme:
the invention provides a polarization-maintaining single-frequency broadening optical fiber amplifying system, which uses a polarization control single-frequency broadening optical fiber amplifier system based on a phase modulation technology of a white noise source.
The method comprises inputting a seed light source seed which can output seed light with narrow line width; the stretcher is used for stretching the narrow-linewidth seed light output by the seed light source and then outputting the stretched narrow-linewidth seed light; the single cladding amplifier is used for carrying out primary amplification on the stretched seed light; the Polarization Controller (PC) is used for carrying out polarization control on the input seed light according to the input control signal so that the polarization of the output light meets the requirement of the input control signal; an Isolator (ISO) for isolating the optical signal output by the polarization controller; the seed light output by the polarization controller can pass through an Isolator (ISO) and then enter the first-stage double-clad amplifier through a first beam combiner COM1 for amplification; the first cladding pumping stripper is used for outputting amplified light through the circulator CIR after redundant pumping light is filtered by the first cladding pumping stripper CPS 1; the mode field adapter is used for changing the mode field of light, coupling the seed optical signal output by the circulator CIR into the optical fiber with large mode field, and then inputting the optical signal into the second-stage double-clad amplifier; the second-stage double-clad amplifier adopts a reverse pumping amplification structure, and pumps light into the double-clad gain fiber through a reverse beam combiner (a reverse coupler) to amplify the seed signal light; the second cladding pump stripper is positioned between the mode field adapter and the second-stage double-cladding amplifier and used for filtering most of redundant pump light; the third cladding pumping stripper is positioned between the second beam combiner and the final laser output head (laser output part) and is used for filtering redundant pumping light output in the forward direction; the amplified seed light output by the second-stage double-clad amplifier passes through a reverse coupler COM2, is output to a final optical fiber output head through a third clad pump stripper CPS 3, and is output through the final optical fiber output head; the first coupling structure couples a small part of laser at the final laser output head, the slow axis light is filtered by a PBS beam splitter, and then an optical signal is converted into an electric signal by a Photoelectric Detector (PD) and is input into a polarization controller so as to control the polarization of the light input into the polarization controller, so that the final output polarization extinction ratio reaches 15 dB.
Preferably, the light source (Seed) is tunable with a center wavelength of 1064 + -0.4 nm, an average power of output light of 50mW-150mW, for example 100mW, and a line width of 10 kHz.
Preferably, the stretcher (Optical stretcher) is composed of two identical phase modulators and two different white noise sources, wherein the frequency of one white noise source is 0.01GHz to 2.5GHz, and the frequency of the other white noise source is 2GHz to 9GHz, so that the line width of the seed light after passing through the stretcher (Optical stretcher) is changed to a line width in the range of 20GHz to 50GHz, preferably a line width of 32GHz can be realized. In other cases, linewidths in the range of 10GHz-80GHz may also be selected.
The polarization controller is used for carrying out polarization control on the input seed light according to the input control signal so that the polarization of the output light meets the requirement of the input control signal; coupling a small part of space light from the final laser output head, filtering slow axis light through a glass sheet type PBS beam splitter, and converting an optical signal into a control (electric) signal by using a Photoelectric Detector (PD).
Preferably, the single clad amplifier uses a semiconductor laser LD 1 with a maximum output power of 500mW-1000mW (for example, a maximum output power of 800mW) and a center wavelength of 976nm as a pump source, and simultaneously couples the pump light and the seed light into the gain fiber PM-YSF-HI (YDF 1) by a Wavelength Division Multiplexer (WDM), and the gain medium is an ytterbium-doped fiber with a length of about 6m-10m, preferably 8 m. The single clad amplifier output power may be equal to or greater than 180mW, for example 200 mW.
Preferably, the second stage double clad amplifier preferably employs a cladding diameter of 400 microns. The light-light conversion efficiency of the second-stage double-clad amplifier is 78%, and the beam quality M2 of the final output laser is approximately equal to 1.2. The first stage double clad amplifier preferably uses a cladding diameter of 125 microns. Preferably, the output power of the seed light output via the CIR is 30W-80W, for example 50W. Preferably, the Mode Field Adapter (MFA) is such that light is transferred from LMA-GDF-10/125 to LMA-GDF-20/400. Preferably, the circulator may employ a three-port circulator.
Preferably, the first-stage double-clad amplifier takes two semiconductor lasers LD2 with the maximum output power of 40W-80W (for example, 60W) and the center wavelength of 976nm as pump sources, the pump light and the seed light are simultaneously coupled into a gain fiber LMA-YDF-10/125(YDF 2) through a beam combiner, and the gain medium is a double-clad ytterbium-doped fiber with the length of 3m-5m, for example, a double-clad ytterbium-doped fiber with the length of 4 m.
Preferably, the second-stage double-clad amplifier takes six semiconductor lasers LD 3 with the maximum output power of 500W-800W (650W for example) and the center wavelength of 976nm as pump sources, the pump light and the seed light are simultaneously coupled into a gain fiber LMA-YDF-25/400(YDF 3) through a reverse beam combiner, and the gain medium is a double-clad ytterbium-doped fiber with the length of 8m-15m, such as a double-clad ytterbium-doped fiber with the length of 11 m.
Preferably, the final output laser can reach an average output power of 3000W, a line width of 20GHz-50GHz, for example, 32GHz, and a polarization extinction ratio of 15 dB.
The invention has the beneficial effects that:
1. the invention provides a polarization-maintaining single-frequency broadening optical fiber amplifying system, which uses a polarization control single-frequency broadening optical fiber amplifier system based on a phase modulation technology of a white noise source. The high-power polarization-maintaining output can be realized by adopting an all-fiber gain amplification structure. The seed light obtains stable broadening through the stretcher consisting of two identical phase modulators and two different white noise sources, so that the power output threshold and the polarization maintaining performance of the whole system are improved.
2. By acquiring part of laser of the final laser output head, slow axis light is filtered by a PBS beam splitter, and then an optical signal is converted into an electric signal by a Photoelectric Detector (PD) and is input into a polarization controller on the front side of a double-clad amplifier so as to control the polarization of the light input into the polarization controller and acquire a very high polarization extinction ratio, and the structure is simple; meanwhile, the polarization control is carried out after the seed light is amplified by the single cladding amplifier, so that the polarization control is more stable and accurate, the subsequent gain amplification is more balanced, the output of high average power can be stably realized, and the excellent polarization control effect can be obtained while the average output power of 3000W is obtained.
3. The second-stage double-clad amplifier adopts a reverse pumping structure to prevent the pump light from directly influencing the final output light, and a second-clad pumping stripper is arranged between the mode field adapter and the second-stage double-clad amplifier to filter most of redundant pump light in the first direction; stripping redundant pump light in a second direction through a third cladding pump stripper CPS 3 between the second beam combiner and the final laser output head; a circulator CIR is arranged behind a pump stripper behind the first-stage double-clad amplifier and is used for exporting residual redundant pump light; namely, the arrangement of back coupling and the cooperation of two pump isolators and a circulator perfectly filter out the redundant pump light, and prevent the influence of the pump light on the output signal such as the collection of optical polarization signals and other possible hazards.
Drawings
In order to more clearly illustrate the present invention or the prior art solutions, the drawings that are needed in the description of the prior art will be briefly described below.
FIG. 1 is a schematic diagram of a polarization-controlled single-frequency broadening amplifier system;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings.
The embodiment of the invention provides a polarization-maintaining single-frequency broadening optical fiber amplification system.
A polarization control single-frequency broadening optical fiber amplifier system based on a white noise source phase modulation technology comprises the following steps:
having an input seed light source seed that can output seed light of narrow linewidth, in some embodiments 10-50kHz, connected to a stretcher by an optical fiber;
and the stretcher is used for stretching the seed light and then outputting the seed light, so that the whole system can achieve higher output power. The stretcher (Optical stretcher) uses a phase modulator to stretch, which in embodiments of the invention may use a white noise source to achieve stretching, changing the linewidth to a linewidth in the range of 10GHz-80GHz, and in some embodiments, in the range of 20GHz-50 GHz.
The inventor realizes that for the polarization-maintaining single-frequency broadening amplification, a single white noise source adopted by the broadening device is easy to cause the problems of unstable line width, uneven broadening and difficult control, and for this purpose, the inventor adopts a designed broadening device, the broadening device (Optical broadening) is composed of two identical phase modulators and two different white noise sources, the two different white noise sources are divided into a first white noise source and a second white noise source, the frequency of the first white noise source is F1, the frequency of the second white noise source is F2, in some embodiments, in order to obtain a more excellent polarization-maintaining effect, the frequency F1 of the first white noise source is 0.01GHz to 2.5GHz, and the frequency F2 of the second white noise source is 2GHz to 9GHz, and then the seed light can be output after being broadened to 10GHz-50GHz, for example, 32 GHz.
The polarization controller is used for carrying out polarization control on the input seed light according to the input control signal so as to enable the polarization of the output light to meet the requirement of the input signal; a small part of laser is coupled from the final laser output head, slow axis light is filtered by a PBS beam splitter, and then an optical signal is converted into a control (electric) signal by using a Photoelectric Detector (PD).
The seed light output after passing through the polarization controller can enter a first-stage double-cladding amplifier for amplification through a first beam combiner COM1 after passing through an Isolator (ISO), and the amplified light is output through a circulator CIR after being filtered by a first cladding pumping stripper CPS 1 (the circulator can adopt a three-port circulator); the output seed light is input into a second-stage double-clad amplifier after passing through a Mode Field Adapter (MFA), the amplified seed light is output through a third clad pump stripper CPS 3 after passing through a second beam combiner COM2, and the beam quality M2 of the final output laser is approximately equal to 1.2. The polarization controller comprises a control optical coupling structure, wherein the control optical coupling structure is used for coupling a small part of laser at a final laser output head, filtering slow axis light through a PBS beam splitter, and converting an optical signal into an electric signal by using a Photoelectric Detector (PD) and inputting the electric signal to the polarization controller.
The isolator is used for preventing the return light generated by the amplifying part at the rear end from being transmitted to the interference and damage possibly generated by the polarization controller.
The final output laser can reach the average output power of 3000W, the line width is 20GHz-50GHz, for example, 32GHz, and the polarization extinction ratio is 15 dB.
The optical fiber, the beam combiner, the converter and the gain amplifying structure behind the Polarization Controller (PC) all affect the polarization maintenance, especially the double-cladding amplifying structure has a large effect on the polarization and affects the final polarization extinction ratio, so it is not suitable to have an excessive number of stages (double-cladding) amplifying structures.
The second stage double clad amplifier preferably uses a cladding diameter of 400 microns (the larger fiber diameter required for the second stage double clad amplifier).
The first stage double clad amplifier preferably uses a cladding diameter of 125 microns. In some embodiments, the output power of the seed light output through the CIR is 30W-80W, such as 50W.
A Mode Field Adapter (MFA) is adapted to allow light to be transferred from LMA-GDF-10/125 to LMA-GDF-20/400.
Therefore, in some embodiments, the first-stage double-clad amplifier uses 2-4 (e.g. 2) semiconductor lasers LD2 with maximum output power of 40W-80W (e.g. 60W) and center wavelength of 976nm as pump sources, and simultaneously couples the pump light and the seed light into the gain fiber LMA-YDF-10/125(YDF 2) through a beam combiner, and the gain medium is a double-clad ytterbium-doped fiber with a length of 3m-5m, e.g. a double-clad ytterbium-doped fiber with a length of 4m (when 2 semiconductor lasers are used as pump sources, the output power of two pump sources can be set to be different, and it has been unexpectedly found that the power ratio of two pump sources can affect the final polarization extinction ratio, when the output power of one pump source is set to be 60W, the output power of the other pump source is gradually increased from 60W to 80W, it was found that in this process, the polarization extinction ratio was improved by 28%, i.e., the output power ratio of the two pump sources was 1:1.2 to 1:1.4 when 2 pump sources were preferred).
In some embodiments, the second-stage double-clad amplifier uses 4-8 (e.g. 6) semiconductor lasers LD 3 with maximum output power of 500W-800W (e.g. 650W) and center wavelength of 976nm as pump sources, and couples the pump light and the seed light into the gain fiber LMA-YDF-25/400(YDF 3) simultaneously through a beam combiner, and the gain medium is a double-clad ytterbium-doped fiber with length of 8m-15m, e.g. 11 m.
Generally, the average output power of the seed light source seed is tens to one or two hundred milliwatts, and referring to the amplification requirement of the first-stage double-clad amplifier, it is known that the input seed light source seed is not beneficial to being output to the first double-clad amplifier after being directly polarization-controlled, and the light power output from the polarization controller is low and is also not beneficial to polarization control.
In some embodiments, the single-clad amplifier uses a semiconductor laser LD 1 with a maximum output power of 500mW-1000mW (e.g., 800mW) and a center wavelength of 976nm as a pump source, and simultaneously couples the pump light and the seed light into a gain fiber PM-YSF-HI (YDF 1) by a Wavelength Division Multiplexer (WDM), wherein the gain medium is ytterbium-doped fiber with a length of about 6m-10m, preferably 8 m. The single clad amplifier output power may be equal to or greater than 180mW, for example 200 mW.
Because the pumping power of the second-stage double-clad amplifier is extremely high, the redundant pumping light is easy to damage devices and influence output, most of the redundant pumping light is filtered by a second-clad pumping stripper (CPS 2) manufactured by using a corrosion process, and because the pumping light power of the second-stage double-clad amplifier is extremely high, even after passing through the pumping stripper, a considerable part of the pump light which is difficult to strip (possibly causing inaccurate acquisition of optical polarization signals) still exists, in order to solve the problem, the invention sets the second-stage double-clad amplifier as a reverse pumping reverse amplification structure, adopts a reverse coupling device, namely a reverse beam combiner (second beam combiner) to couple the pumping light into the gain fiber, sets the second-clad pumping stripper between the mode field adapter and the second-stage double-clad amplifier to filter most of the redundant pumping light in the first direction, then leading out the residual redundant pump light in the first direction through a circulator between the first cladding pumping stripper and the mode field adapter; then, since a part of the pump light in the second direction is also generated after the pump light in the reverse amplification structure is reflected by the front-end device, since the part of the pump light is very little, the pump light can be stripped by the third cladding pump stripper CPS 3 between the second beam combiner and the final laser output head.
In some embodiments, the circulator may employ a three-port circulator.
As a general knowledge in the field of optical fiber amplification systems, functional devices of a polarization-maintaining single-frequency-broadening optical fiber amplification system are sequentially connected through optical fibers, in some embodiments, a seed light source is connected to a stretcher through an optical fiber, the stretcher is connected to a single-clad amplifier through an optical fiber, the single-clad amplifier is connected to a polarization control device through an optical fiber, the polarization control device is connected to an isolator through an optical fiber, the isolator is connected to a first-stage double-clad amplifier through an optical fiber, the first-stage double-clad amplifier is connected to a circulator through an optical fiber, the circulator is connected to a mode field adapter through an optical fiber, the mode field adapter is connected to a second-stage double-clad amplifier through an optical fiber, and the second-stage double-clad amplifier is connected to a laser output head through an optical fiber; the first, second and third cladding pumping strippers are also fabricated on the fiber structure by etching process.
Referring to fig. 1, a specific embodiment is illustrated as follows:
in some embodiments, the light source (Seed) is tunable with a center wavelength of 1064 + -0.4 nm, an average power of output light of 50mW to 150mW, such as 100mW, and a linewidth of 10 to 50kHz, such as 10 kHz.
The stretcher (Optical stretcher) is composed of two identical phase modulators and two different white noise sources, wherein the frequency of one white noise source is 0.01GHz to 2.5GHz, the frequency of the other white noise source is 2GHz to 9GHz, the line width of seed light after passing through the stretcher (Optical stretcher) is changed to 32GHz, and the whole system can achieve higher output power.
The single-clad amplifier takes a semiconductor laser LD 1 with the maximum output power of 800mW and the center wavelength of 976nm as a pumping source, and simultaneously couples pumping light and seed light into a gain fiber PM-YSF-HI (YDF 1) through a Wavelength Division Multiplexer (WDM), wherein a gain medium is an ytterbium-doped fiber with the length of 8 m. The output power of the single-clad amplifier is 200mW, and the seed light firstly passes through a Polarization Controller (PC) and then enters the first-stage double-clad amplifier through ISO. The first-stage double-clad amplifier takes two semiconductor lasers LD2 with the maximum output power of 60W and the center wavelength of 976nm as pumping sources, and couples pumping light and seed light into a gain fiber LMA-YDF-10/125(YDF 2) through a beam combiner, wherein a gain medium is a double-clad ytterbium-doped fiber with the length of 4 m. After the CPS 1 filters the redundant pump light, the pump light is output through the CIR, and the output power is 50W. The seed light is input into a second-stage double-clad amplifier (namely, the seed light is input into a gain fiber YDF 3) after being converted into a Mode Field Adapter (MFA) of an LMA-GDF-20/400 by an LMA-GDF-10/125. The second-stage double-clad amplifier takes six semiconductor lasers LD 3 with the maximum output power of 650W and the central wavelength of 976nm as pumping sources, and simultaneously couples pumping light and seed light into a gain fiber LMA-YDF-25/400(YDF 3) through a reverse beam combiner, wherein a gain medium is a double-clad ytterbium-doped fiber with the length of 11 m. And the stress of the gain fiber is ensured to be as small as possible in the winding process of the YDF 3, so that the polarization extinction ratio of the final output laser is ensured. The second-stage double-clad amplifier is of a reverse amplification structure, redundant pumping light is filtered by a clad pump stripper (CPS 2) manufactured by using a corrosion process, the amplified seed light passes through COM2 and then is output through CPS 3, the output average power is 3000W, and the line width is 32 GHz. The light-light conversion efficiency of the second-stage double-clad amplifier is 78%, and the beam quality M2 of the final output laser is approximately equal to 1.2. Coupling a small part of laser at the final laser output head, filtering slow axis light through a PBS beam splitter, converting an optical signal into an electric signal by using a Photoelectric Detector (PD), and inputting the electric signal into a polarization controller, so that the final output polarization extinction ratio reaches 15 dB. Compared with a full polarization maintaining structure, the non-linear threshold value is improved, and the manufacturing cost is reduced.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A single-frequency broadening optical fiber amplifying system comprises,
a seed light source for outputting seed light;
the stretcher is used for stretching the seed light output by the seed light source and then outputting the stretched seed light;
the polarization controller is used for carrying out polarization control on the input seed light according to an input control signal;
the first-stage double-clad amplifier is used for outputting the seed light after the seed light passes through the polarization controller and enters the first-stage double-clad amplifier for amplification and then outputting the seed light;
the second-stage double-clad amplifier amplifies the light amplified by the first-stage double-clad amplifier and outputs the amplified light;
and obtaining part of light in the output light of the second-stage double-clad amplifier, filtering the slow axis light of the part of light by using a PBS beam splitter, inputting the filtered slow axis light to a photoelectric detector, and converting an optical signal obtained by the photoelectric detector into a control signal by using the photoelectric detector and inputting the control signal to a polarization controller.
2. The single-frequency broadening fiber amplifying system as claimed in claim 1, wherein the seed light outputted from the seed light source is broadened and inputted to the single clad amplifier via a Wavelength Division Multiplexer (WDM), and then inputted to the polarization controller after being amplified by the single clad amplifier.
3. The single-frequency broadened optical fiber amplifying system according to claim 1, wherein the seed light output by the seed light source is a narrow linewidth laser.
4. The single-frequency broadened optical fiber amplification system according to claim 3, wherein the linewidth of the seed light output by the seed light source is 10-50kHz, the stretcher comprises two identical phase modulators and two different white noise sources, the first white noise source has a frequency of 0.01GHz to 2.5GHz, and the second white noise source has a frequency of 2GHz to 9 GHz.
5. The single-frequency broadened optical fiber amplification system according to claim 1, comprising an Isolator (ISO) located behind the polarization controller for isolating the optical signal output by the polarization controller; the seed light output after passing through the polarization controller can enter a first-stage double-clad amplifier for amplification through a first beam combiner after passing through an Isolator (ISO).
6. The single-frequency broadened optical fiber amplification system of claim 1, comprising a first cladding pump stripper located after the first stage double-clad amplifier, the amplified light being output through the circulator CIR after being filtered of excess pump light by the first cladding pump stripper.
7. The single-frequency broadened optical fiber amplification system according to claim 1, comprising a mode field adapter for inputting a signal amplified by the first-stage double-clad amplifier into the second-stage double-clad amplifier after changing a mode field, wherein a core diameter of the gain fiber of the first-stage double-clad amplifier is smaller than a core diameter of the gain fiber of the second-stage double-clad amplifier, and a cladding diameter of the gain fiber of the first-stage double-clad amplifier is smaller than a cladding diameter of the gain fiber of the second-stage double-clad amplifier.
8. The single-frequency broadened optical fiber amplification system according to claim 1, wherein the second-stage double-clad amplifier is a reverse amplification structure of a reverse pump, a reverse coupler is adopted to couple pump light into the gain optical fiber, and a second clad pump stripper is arranged at the front end of the second-stage double-clad amplifier and is used for filtering redundant pump light in the first direction; a circulator is disposed between the first stage double-clad amplifier and the second stage double-clad amplifier, the circulator being capable of deriving return light from a subsequent amplifier.
9. The single-frequency broadened optical fiber amplifying system according to claim 8, wherein the amplified seed light output from the second-stage double-clad amplifier passes through the third cladding pump stripper after passing through the back coupler, and then is output to the laser output head.
10. The single-frequency broadened optical fiber amplification system according to claim 4, wherein the linewidth of seed light after passing through the stretcher is changed to be within the range of 20GHz-50GHz, the first-stage double-clad amplifier takes 2-4 semiconductor lasers LD2 with the maximum output power of 40W-80W as a pumping source, the pumping light and the seed light are simultaneously coupled into the gain optical fiber LMA-YDF-10/125 through a beam combiner, the gain medium is a double-clad ytterbium-doped fiber with the length of 3m-5m, the second-stage double-clad amplifier takes 4-8 semiconductor lasers LD 3 with the maximum output power of 500W-800W as a pumping source, the pumping light and the seed light are simultaneously coupled into the gain optical fiber LMA-YDF-25/400 through the beam combiner, and the gain medium is a double-clad ytterbium-doped fiber with the length of 8m-15 m.
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| CN104901154A (en) * | 2015-05-07 | 2015-09-09 | 中国科学院物理研究所 | Laser spreading device and method based on white Gaussian noise |
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| CN109346911A (en) * | 2018-12-22 | 2019-02-15 | 北京工业大学 | A kind of tens of megahertzs of Gao Zhongying nanoseconds full optical fiber laser amplifier |
| CN112787207A (en) * | 2021-02-05 | 2021-05-11 | 中国人民解放军国防科技大学 | High-power narrow linewidth optical fiber laser based on ring cavity oscillator seed source |
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- 2021-12-19 CN CN202111585991.0A patent/CN114430139A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104901154A (en) * | 2015-05-07 | 2015-09-09 | 中国科学院物理研究所 | Laser spreading device and method based on white Gaussian noise |
| CN108512028A (en) * | 2018-05-29 | 2018-09-07 | 中国人民解放军国防科技大学 | System for inhibiting mode instability in high-power optical fiber laser amplifier |
| CN109346911A (en) * | 2018-12-22 | 2019-02-15 | 北京工业大学 | A kind of tens of megahertzs of Gao Zhongying nanoseconds full optical fiber laser amplifier |
| CN112787207A (en) * | 2021-02-05 | 2021-05-11 | 中国人民解放军国防科技大学 | High-power narrow linewidth optical fiber laser based on ring cavity oscillator seed source |
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