MOPA fiber laser for wind measurement radar

Abstract

This invention discloses a MOPA fiber laser for wind measurement radar, comprising a seed source, a beam splitter, an expansion module, a first-stage amplification module, a second-stage amplification module, and an output module. The seed source provides a low-power initial laser beam, which is then split by the beam splitter. The split laser beam enters the expansion module, forming a closed-loop optical path, and then outputs a highly stable seed light signal with specific parameters to the first-stage amplification module. The first amplification module performs a first-stage amplification of the seed light signal, the second amplification module performs a second-stage amplification of the first-stage amplified laser, and the output module controls the output of the laser after the second-stage amplification. This invention eliminates redundant acousto-optic modulators and pump protectors in the amplification optical path compared to existing technologies, and optimizes the optical path, effectively reducing the number of optical components and saving costs.

Description

Technical Field

[0001] This utility model relates to a device for wind measuring radar, and more particularly to a MOPA fiber laser for wind measuring radar. Background Technology

[0002] A wind-measuring radar is a meteorological detection device used to measure wind field parameters such as wind speed and direction. Its core function is to accurately monitor the atmospheric wind field by emitting sound waves or laser pulses and utilizing the Doppler frequency shift principle or reflection signal analysis. It is mainly used in the wind power industry, meteorological early warning and scientific research, and aviation and public safety. In the wind power field: it is used for micro-site selection of wind farms, power generation assessment, and wind turbine layout optimization, and can replace traditional wind-measuring towers, reducing the construction cost of offshore wind power. In the meteorological early warning and scientific research field: it monitors extreme weather (such as turbulence and wind shear), providing real-time data for meteorological early warning; research institutions use it to create three-dimensional wind field models and study the atmospheric boundary layer. In the aviation and public safety field: it ensures the safety of aircraft takeoff and landing at airports, assisting flight scheduling with real-time wind field data; and provides high-precision meteorological support during major events (such as military parades).

[0003] Wind speed and direction measurements are typically measured using sound waves. Sound radar emits directional sound pulses and receives their scattered echoes, calculating wind speed and direction based on the propagation characteristics of sound waves in the atmosphere (such as frequency differences). Laser radar, on the other hand, uses laser pulses. It emits laser pulses and calculates distance and velocity by measuring the time-of-flight (ToF) or frequency modulation (FMCW) echo. By using extremely short wavelength lasers, it can generate high-precision three-dimensional point clouds, directly measuring the movement of airborne dust particles. Compared to sound radar, laser radar has significant advantages in detection altitude, accuracy, resolution, anti-interference capability, and environmental adaptability; therefore, most wind radars currently use lasers for measurement.

[0004] With the continuous development of laser technology, MOPA fiber lasers (Master Oscillator Power-Amplifier Fiber Laser, abbreviated as MOPA fiber laser) have seen further improvements in performance, stability, and reliability; therefore, they are widely used in wind measurement radar. MOPA fiber lasers specifically refer to nanosecond pulsed fiber lasers based on a master oscillator and multi-stage power amplifiers, which easily achieve tunable and modulated laser output. Originating in the early 1990s, MOPA fiber lasers were developed based on the need for single-frequency high-power lasers. By selecting a seed source with a certain repetition frequency and pulse width as the master oscillator, and then amplifying the power, the required high-energy pulsed laser output can be obtained. This laser has the same wavelength and repetition frequency as the seed source, and the pulse shape and width are almost unchanged. In recent years, with the continuous development of MOPA fiber lasers and wind lidar, market competition has become increasingly fierce, posing severe challenges to the cost and performance of equipment. Existing MOPA fiber lasers used in wind lidar, such as... Figure 1 As shown: Seed source 1 outputs a low-power initial laser (i.e., seed light, seed signal), which enters beam splitter 2 and splits into two branches; Branch 1: Part of the seed signal directly enters coupler 3 and waits for the other beam to scatter back before merging and coupling with it; Branch 2: The other part of the seed signal passes sequentially through the first AOM4 (Acousto-Optic Modulator), WDM5 (Wavelength Division Multiplexer), and is optically coupled to the first-stage pump source 7 (protected by pump protector 6), and together injected into the first-stage active fiber EDF8 (Erbium Doped). The first stage of amplification is achieved using erbium-doped fiber (EDF). The amplified laser light is then filtered by isolation filter 9' to remove interference before entering the second AOM 10' for pulse modulation. It is then optically coupled to the second-stage pump source 12' via combiner 11', and injected into the second-stage active fiber EYDF 13' (Erbium-Ytterbium Co-doped Double-cladding Fiber) for further amplification. The amplified laser light then enters circulator 14' and is output to optical switch 15'. Optical switch 15' adjusts the pulse sequence of the output laser by switching channels. The laser pulse is injected into the air through a lens, and its scattered echo signal enters coupler 3' to couple with the seed signal input from branch 1 to form the desired target laser output. The existing MOPA fiber lasers used in wind measurement radars have the following drawbacks: (1) they have a large number of optical components, resulting in high costs and complicated operation; (2) they have slightly lower average output power and poorer performance.

[0005] Therefore, there is an urgent need for a MOPA fiber laser for wind measurement radar that can improve the average power and output stability of laser output, while also saving costs and simplifying operation. Utility Model Content

[0006] The purpose of this invention is to provide a MOPA fiber laser for wind measurement radar, which can improve the average power and stability of laser output, as well as save costs and simplify operation.

[0007] To achieve the above objectives, this utility model provides a MOPA fiber laser for wind measurement radar, which includes: Seed source used to provide low-power initial laser; A beam splitter is connected to the seed source optical path. The beam splitter receives the initial laser and splits the initial laser into a first split laser and a second split laser. The expansion module includes a first circulator, an acousto-optic modulator, and a first coupler. The optical fibers at the output ports of the first coupler are fused together, and the first circulator, the acousto-optic modulator, and the first coupler are sequentially connected to form a closed-loop optical path.

[0008] The first-stage amplification module includes an isolation filter, a wavelength division multiplexer (WDM), and a first-stage pump source. The WDM and the isolation filter are connected via a first-stage active fiber optic EDF (Electronic Direct Current Filter). The wavelength division multiplexer outputs light from the first split laser beam through the expansion module and combines it with the light from the first-stage pump source. The combined beam is then injected into the first-stage active fiber EDF for first-stage amplification. The first-stage amplified laser beam is filtered by an isolation filter to isolate the reverse light. The secondary amplification module includes a secondary pump source, a beam combiner, and a second circulator, which are connected in sequence via optical paths. The beam combiner and the second circulator are connected via a secondary active optical fiber (EYDF). The beam combiner is connected to the isolation filter and receives the primary amplified laser light after filtering and isolating the reversed light. The primary amplified laser light is combined with the light from the secondary pump source and then injected into the secondary active optical fiber (EYDF) for secondary amplification. The secondary amplified laser light is then transmitted to the second circulator. The output module includes a second coupler and an optical switch. The second coupler and the optical switch are optically connected to the second circulator. The second coupler is also connected to the second split laser beam. The secondary amplified laser beam enters the optical switch through the second circulator. The optical switch adjusts the pulse sequence of the output laser by switching channels. The laser pulse sequence is scattered into the air after passing through the lens, and the echo signal enters the second coupler through the optical switch and the second circulator. This signal light couples with the second split laser beam in the second coupler and outputs the laser beam.

[0009] Compared with existing technologies, the seed source of this invention outputs an initial laser (i.e., seed light, seed signal). The seed light is split into a first split laser and a second split laser by a first beam splitter. The first split laser forms the main seed light for seed light signal expansion and two-stage amplification. The second split laser serves as an auxiliary path, transmitting the seed signal to a second coupler where it is coupled with the echo signal from another path of light scattering. The seed light is output to the expansion module by the first circulator. Since the first circulator, acousto-optic modulator, and first coupler are sequentially connected to form a closed-loop optical path, the seed light is isolated and protected by the first circulator. The acousto-optic modulator pulses the seed light, which is then split and fused by the first coupler to form a closed-loop optical path. This achieves regeneration, amplification, shaping, and phase locking of the modulated pulse, providing a highly stable seed light signal with specific parameters for subsequent power amplification and providing an expansion channel. Specifically, the first-stage amplification process involves the seed light signal passing through a first circulator and then being combined with the light from a first-stage pump source in a wavelength division multiplexer before entering a first-stage active EDF fiber. The pump energy induces stimulated emission of rare-earth ions in the EDF, amplifying the seed light. An isolation filter removes interference and isolates the reverse light to ensure unidirectional transmission. The second-stage amplified laser light then passes through a beam combiner and a second-stage pump source before entering a second-stage active EYDF fiber. Higher power pumping further amplifies the laser energy to the target level. The amplified laser light then passes through a second circulator and enters an optical switch. The optical switch adjusts the output laser pulse sequence by switching channels. The laser pulse sequence is reflected back through a lens into the air. This reflected signal passes through the optical switch and the second circulator into a second coupler. This signal light couples with the second split laser beam in the second coupler to output the final laser beam. As can be seen from the above, this invention eliminates redundant acousto-optic modulators and pump protectors in the optical path of the output laser pulse, and optimizes the optical path; it effectively reduces the number of optical components, saving costs; due to the reduction of optical components, the debugging difficulty and time for debugging personnel are reduced, simplifying operation; and due to the reduction of optical components and the optimization of the optical path, the optical loss in the transmission process is effectively reduced, thereby improving the average output power and performance; it effectively solves the technical problems existing in the prior art.

[0010] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the optical path connection between the primary pump source and the wavelength division multiplexer is via fiber fusion splicing. Utilizing the low-loss transmission characteristics of optical fiber, the pump light is efficiently injected into the wavelength division multiplexer and combined with the seed light before entering the gain fiber. This reduces the use of fiber optic connectors, saving costs and reducing optical loss, further improving the average output power and performance.

[0011] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the optical path connection between the isolation filter and the combiner is achieved through fiber fusion splicing. Fiber fusion splicing enables a permanent optical connection, minimizing optical loss at the fiber interface and further improving the average output power and performance.

[0012] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the optical path connection between the first circulator, the beam splitter, and the wavelength division multiplexer is fiber optic fusion splicing. Fiber optic fusion splicing achieves a permanent optical connection, minimizing optical loss at the fiber interface and further improving the average output power and performance.

[0013] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the core diameter of the primary active fiber EDF is 7 micrometers and the cladding diameter is 125 micrometers.

[0014] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the core diameter of the secondary active fiber EYDF is 12 micrometers and the cladding diameter is 130 micrometers.

[0015] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the modulation bandwidth of the acousto-optic modulator is 80MHz.

[0016] Preferably, in the MOPA fiber laser for wind measurement radar of this invention, the isolation filter includes a series-connected optical isolation unit and a narrowband bandpass filter unit. The optical isolation unit is used to isolate the backlight of the first-stage amplified laser, and the narrowband bandpass filter unit is used to suppress noise and remove interference from the first-stage amplified laser. The two work together to improve the stability and beam quality of the output laser of this invention. Attached Figure Description

[0017] Figure 1 This is a diagram of the optical path structure of the MOPA fiber laser used in existing wind measurement radar.

[0018] Figure 2 This is a schematic diagram of the optical path structure of the MOPA fiber laser used in wind measurement radar according to this utility model. Detailed Implementation

[0019] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0020] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0021] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0022] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0023] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0024] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0025] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0026] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0027] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0028] In view of the deficiencies in the existing technology, the applicant, based on years of practical experience and professional knowledge in the design and manufacture of such products, and in conjunction with the application of theoretical principles, has actively conducted research and innovation in order to create a technology that can solve the deficiencies in the existing technology. After continuous research, design, and repeated prototype production and improvement, this utility model with practical value has finally been created.

[0029] like Figure 2 As shown, the MOPA fiber laser for wind measurement radar of this invention includes a seed source 1 for providing a low-power initial laser, which is also referred to as seed light or seed signal in the art. The MOPA fiber laser for wind measurement radar of this invention also includes a beam splitter 2 for splitting the initial laser, an expansion module for providing an expansion channel for the split laser, a first-stage amplification module for performing a first-stage amplification of the expanded laser, a second-stage amplification module for performing a second-stage amplification of the first-stage amplified laser, and an output module for controlling the output of the second-stage amplified laser. The following continues in conjunction with... Figure 2 A more detailed description of the MOPA fiber laser used in this wind-measuring radar is provided below: The beam splitter 2 of this invention is connected to the optical path of the seed source 1. The beam splitter 2 receives the initial laser beam and splits it into two seed beams, namely a first split laser beam 21 and a second split laser beam 22. The first output port of the beam splitter 2 outputs the first split laser beam 21, and the second output port outputs the second split laser beam 22. The first split laser beam 21 is used for expansion and secondary amplification, and the second split laser beam 22 is used to merge and couple with the echo signal scattered from another path to output laser light.

[0030] like Figure 2 As shown, to expand the applications and characteristics of the output laser, this invention also includes an expansion module. This expansion module includes an acousto-optic modulator 14 (AOM) and a first coupler 15. The second port of the first circulator 4 is optically connected to the acousto-optic modulator 14, which in turn is optically connected to the first coupler 15. The optical fibers at the output port 151 of the first coupler 15 are fused together. The first circulator 4, the acousto-optic modulator 14, and the first coupler 15 are sequentially optically connected to form a closed-loop optical path, thus constituting the expansion module of this invention. Specifically, the first coupler 15 of this invention is a 1×2 coupler. Specifically, the first port of the first circulator 4 is optically connected to the first output port of the beam splitter 2, and the second port of the first circulator 4 is optically connected to the acousto-optic modulator 14. The first split laser beam 21 is output from the second port of the first circulator 4 to the expansion module. Since the first circulator 4, the acousto-optic modulator 14 and the first coupler 15 are connected in sequence to form a closed-loop optical path, the seed light is isolated and protected by the first circulator 4. The seed light is pulse-modulated by the acousto-optic modulator 14, and then split and fused by the first coupler 15 to form a closed-loop optical path, realizing the regeneration, amplification, shaping and phase locking of the modulated pulse, providing an expansion channel for a seed light signal with high stability and specific parameters for subsequent power amplification.

[0031] like Figure 2 As shown, the first-stage amplification module of this invention receives and amplifies the extended laser light. This first-stage amplification module includes an isolation filter 3 and, in sequence, a first circulator 4, a wavelength division multiplexer 5 (WDM), and a first-stage pump source 6, all connected by optical paths. The WDM and the isolation filter 3 are connected via a first-stage active fiber optic cable (EDF7). Specifically, the first port of the first circulator 4 is optically connected to the first output port of the beam splitter 2, the third port of the first circulator 4 is optically connected to the WDM 5, and the first-stage pump source 6 is optically connected to the WDM 5. This allows the WDM 5 to receive and combine the extended laser light received from the first circulator 4 with the light from the first-stage pump source 6. The combined laser beam is then injected into the first-stage active fiber optic cable (EDF7) for first-stage amplification. The amplified laser light is filtered by the isolation filter 3, which isolates the reverse light, before being input into the second-stage amplification module for second-stage amplification.

[0032] like Figure 2 As shown, the secondary amplification module of this invention performs secondary amplification on the primary amplified laser light after filtering and isolating the reverse light. The secondary amplification module includes a secondary pump source 8, a beam combiner 9, and a second circulator 10, which are connected in sequence via optical paths. The beam combiner 9 and the second circulator 10 are connected via a secondary active optical fiber EYDF11. Specifically, the input end of the beam combiner 9 is connected to the output end of the isolation filter 3 and the optical path of the secondary pump source 8, respectively. This allows the beam combiner 9 to receive the primary amplified laser light after filtering and isolating the reverse light from the isolation filter 3 and combine it with the light from the secondary pump source 8. The combined beam is then injected into the secondary active optical fiber EYDF11 for secondary amplification. The secondary amplified laser light is transmitted to the first port of the second circulator 10 as the desired laser target and enters the output module for output.

[0033] like Figure 2 As shown, the output module of this invention receives a secondary amplified laser and outputs the desired target laser. Specifically, the output module includes a second coupler 12 and an optical switch 13. The optical switch 13 is connected to the second port optical path of the second circulator 10, allowing the secondary amplified laser to be transmitted to the optical switch 13 via the second circulator 10. The optical switch 13 adjusts the pulse sequence of the output laser by switching channels. The optical switch 13 can be configured with multiple channels, such as four, five, or six channels, depending on actual needs. Furthermore, the input end of the second coupler 12 is connected to the third port optical path of the second circulator 10, allowing the scattered echo signal of the laser pulse sequence after passing through the lens and entering the air to enter the second coupler 12 via the optical switch 13 and the second circulator 10. The input end of the second coupler 12 is also connected to the second output port optical path of the beam splitter 2, allowing the second split laser 22 to be transmitted to the second coupler 12. Specifically, the second coupler 12 is a 2×2 coupler. Therefore, the second coupler 12 simultaneously receives the second split laser beam 22 (as seed light) and the scattered echo signal after the laser pulse sequence enters the air through the lens. The second coupler 12 combines and couples them to finally output the desired target laser (i.e., laser pulse).

[0034] At the same time, such as Figure 2As shown, the seed source 1 of this invention outputs seed light. This seed light is split into a first split laser 21 and a second split laser 22 by a first beam splitter 2. The first split laser 21 forms the main seed light path for seed light signal expansion and two-stage amplification. The second split laser 22 serves as an auxiliary path, transmitting the seed signal to a second coupler 12 where it is coupled with the echo signal from another beam. This invention isolates and protects the seed light (i.e., the first split laser 21) using a first circulator 4, pulse-modulates the seed light (i.e., the first split laser 21) using an acousto-optic modulator 14, and then splits and fuses the beams through a first coupler 15 to form a closed-loop optical path expansion module. This achieves regeneration, amplification, shaping, and phase locking of the modulated pulse, providing a highly stable seed light signal with specific parameters for subsequent power amplification. Specifically, the first-stage amplification involves the following steps: First-stage amplification: The seed signal light from the main path extension enters the wavelength division multiplexer (WDM) 5 via the first circulator 4 and is combined with the light from the first-stage pump source 6 before entering the first-stage active EDF fiber 7. The pump energy causes stimulated emission of rare-earth ions in the EDF, amplifying the seed light. The isolation filter 3 filters out interference and isolates the reverse light to ensure unidirectional transmission. Second-stage amplification: The laser light amplified in the first stage enters the second-stage active EYDF fiber 11 via the beam combiner 9 and the light from the second-stage pump source 8. Higher power pumping is used for secondary amplification, further increasing the laser energy to the target level. The amplified laser light is then transmitted to the optical switch 13 via the second circulator 10. The optical switch 13 adjusts the output laser pulse sequence by switching channels. The second coupler 12 couples the second split laser 22 transmitted from the auxiliary path with the scattered echo signal after the laser pulse sequence is injected into the air through the lens, ultimately outputting the desired target laser pulse. As can be seen from the above, this invention eliminates redundant acousto-optic modulators and pump protectors in the optical path of the output target laser pulse, and optimizes the optical path; it effectively reduces the number of optical components, saving costs; due to the reduction of optical components, the debugging difficulty and time for debugging personnel are reduced, simplifying operation; and due to the reduction of optical components and the optimization of the optical path, the optical loss in the transmission process is effectively reduced, thereby improving the average output power and performance; it effectively solves the technical problems existing in the prior art.

[0035] like Figure 2 As shown, preferably, in this practical MOPA fiber laser for wind measurement radar, the optical path connection between the first-stage pump source 6 and the wavelength division multiplexer 5 is via fiber fusion splicing. The output pigtail of the first-stage pump source 6 is fused to the fiber at the pump light input end of the wavelength division multiplexer 5; utilizing the low-loss transmission characteristics of optical fiber, the pump light is efficiently injected into the wavelength division multiplexer, and after being bundled with the seed light, it enters the gain fiber, reducing the use of fiber optic connectors (such as FC / APC), saving costs, reducing optical loss, and further improving the average output power and performance.

[0036] like Figure 2 As shown, preferably, in this practical MOPA fiber laser for wind measurement radar, the optical path connection between the isolation filter 3 and the combiner 9 is a fiber fusion splice. The output fiber of the isolation filter 3 is fused to the signal light input fiber of the combiner 9. The optical path connection between the first circulator 4, the beam splitter 2, and the wavelength division multiplexer 5 is also a fiber fusion splice. Permanent optical connection is achieved through fiber fusion splicing, minimizing optical loss at the fiber interface and ensuring efficient transmission of the laser after first-stage amplification to the second-stage amplification link. It also reduces the use of fiber optic connectors (such as FC / APC), saving costs and improving optical loss, further enhancing the average output power and performance.

[0037] To further improve the average output power and performance of the laser output of this invention, the following improvements have been made: the core diameter of the primary active optical fiber EDF7 is 7 micrometers, and the cladding diameter is 125 micrometers. The core diameter of the secondary active optical fiber EYDF11 is 12 micrometers, and the cladding diameter is 130 micrometers. The modulation bandwidth of the acousto-optic modulator is 80MHz.

[0038] like Figure 2 As shown, preferably, in the MOPA fiber laser for wind measurement radar of this invention, the isolation filter 3 includes a series-connected optical isolation unit and a narrowband bandpass filter unit. The optical isolation unit is used to isolate the backlight of the first-stage amplified laser, and the narrowband bandpass filter unit is used to suppress noise and remove interference from the first-stage amplified laser. The two work together to improve the stability of the output laser and the quality of the output beam of this invention.

[0039] Furthermore, the working principle and structure of the optical devices involved in this utility model are well known to those skilled in the art, and will not be described in detail here.

[0040] It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this utility model is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, the embodiments disclosed above are merely preferred embodiments of this utility model and should not be construed as limiting the scope of this utility model. Therefore, equivalent variations made within the scope of the claims of this utility model are still within the scope of this utility model.

Claims

1. A MOPA fiber laser for wind measurement radar, characterized in that, include: Seed source used to provide low-power initial laser; A beam splitter is connected to the seed source optical path. The beam splitter receives the initial laser and splits the initial laser into a first split laser and a second split laser. The expansion module includes a first circulator, an acousto-optic modulator, and a first coupler. The optical fibers at the output ports of the first coupler are fused together, and the first circulator, the acousto-optic modulator, and the first coupler are sequentially connected to form a closed-loop optical path. The first-stage amplification module includes an isolation filter, a wavelength division multiplexer (WDM), and a first-stage pump source. The WDM and the isolation filter are connected via a first-stage active fiber optic EDF (Electronic Direct Current Filter). The wavelength division multiplexer outputs light from the first split laser beam through the expansion module and combines it with the light from the first-stage pump source. The combined beam is then injected into the first-stage active fiber EDF for first-stage amplification. The first-stage amplified laser beam is filtered by an isolation filter to isolate the reverse light. The secondary amplification module includes a secondary pump source, a beam combiner, and a second circulator, which are connected in sequence via optical paths. The beam combiner and the second circulator are connected via a secondary active optical fiber (EYDF). The beam combiner is connected to the isolation filter and receives the primary amplified laser light after filtering and isolating the reversed light. The primary amplified laser light is combined with the light from the secondary pump source and then injected into the secondary active optical fiber (EYDF) for secondary amplification. The secondary amplified laser light is then transmitted to the second circulator. The output module includes a second coupler and an optical switch. The second coupler and the optical switch are optically connected to the second circulator. The second coupler is also connected to the second split laser beam. The secondary amplified laser beam enters the optical switch through the second circulator. The optical switch adjusts the pulse sequence of the output laser by switching channels. The laser pulse sequence is scattered into the air after passing through the lens, and the echo signal enters the second coupler through the optical switch and the second circulator. This signal light couples with the second split laser beam in the second coupler and outputs the laser beam.

2. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The optical path connection between the primary pump source and the wavelength division multiplexer is optical fiber fusion splicing.

3. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The optical path connection between the isolation filter and the beam combiner is an optical fiber fusion splice.

4. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The optical path connection between the first circulator, the beam splitter, and the wavelength division multiplexer is fiber optic fusion splicing.

5. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The core diameter of the primary active optical fiber (EDF) is 7 micrometers, and the cladding diameter is 125 micrometers.

6. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The core diameter of the secondary active optical fiber EYDF is 12 micrometers, and the cladding diameter is 130 micrometers.

7. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The modulation bandwidth of the acousto-optic modulator is 80MHz.

8. The MOPA fiber laser for wind measurement radar according to claim 1, characterized in that, The isolation filter includes an optical isolation unit connected in series with optical paths and a narrowband bandpass filter unit.

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