Switchable output wavelength laser, laser system and wind finding radar

Abstract

The invention provides a switchable output wavelength laser, a laser system and a wind finding radar, and relates to the technical field of lasers, the laser comprises a pumping structure, a first optical fiber, a filtering structure and a wavelength switching structure, and the wavelength switching structure comprises a second optical fiber and an adjusting structure. The first optical fiber generates a second light beam based on a first light beam emitted by the pumping structure, the filtering structure filters the second light beam to obtain at least two target light beams, the second optical fiber obtains an output light beam based on the at least two target light beams, and the adjusting structure adjusts the bending degree of the second light beam and different bending degrees of the second optical fiber. And different wavelengths of the output light beams are correspondingly output. The laser can output laser beams with various wavelengths, and wavelength selection of the output beams can be realized through the bending degree of the second optical fiber. Meanwhile, wavelength selection of the output light beams is achieved through the bending degree of the second optical fiber, flexible switching of the output light beams with different wavelengths can be achieved, and repeatability is achieved.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a laser with switchable output wavelength and a laser system. Background Art

[0002] With the rapid development of the semiconductor industry, the application fields of lasers are becoming more and more extensive, for example, material processing, fiber optic sensing, spectroscopy, lidar systems and other fields.

[0003] However, with the widespread application of lasers, the application scenarios of lasers are becoming more and more diverse. When the same laser is used in different application scenarios, since the laser wavelengths required for different application scenarios are not the same, it is necessary for the laser to be able to output lasers of different wavelengths, and the wavelength of the output laser can be selected. Summary of the invention

[0004] In view of this, the present application provides a switchable output wavelength laser, the scheme is as follows:

[0005] A switchable output wavelength laser comprises: a pump structure, a first optical fiber, a filter structure and a wavelength switching structure;

[0006] The pump structure is used to generate a first light beam;

[0007] The first optical fiber receives the first light beam, generates a second light beam based on the first light beam, and transmits the second light beam to the filtering structure;

[0008] The filtering structure filters the second light beam to obtain at least two target light beams, the wavelengths of the at least two target light beams are different, and the wavelengths of the at least two target light beams are within the wavelength range of the second light beam;

[0009] The filtering structure transmits the at least two target light beams to a wavelength switching structure, which includes a second optical fiber and an adjustment structure. The second optical fiber obtains an output light beam based on the at least two target light beams, and the output light beam is one of the at least two target light beams. The adjustment structure is used to adjust the bending degree of the second optical fiber, and different bending degrees of the second optical fiber correspond to different wavelengths of the output light beam.

[0010] Optionally, the wavelength switching structure further comprises a circulator, a first port of the circulator is connected to the first optical fiber, a second port of the circulator is connected to one end of the second optical fiber, a third port of the circulator is connected to the other end of the second optical fiber, the at least two target light beams enter the second optical fiber through the first port and the second port of the circulator in sequence, and the output light beam is output through the third port and the first port of the circulator in sequence;

[0011] The second optical fiber includes a first part and a second part that are connected, and one end of the first part is connected to the first port of the circulator, and one end of the second part is connected to the third port of the circulator; the adjustment structure includes a first displacement stage and a second displacement stage, the first displacement stage is a movable displacement stage, the first displacement stage drives the first part to move, and adjusts the bending degree of the first part so that the first part obtains the output light beam based on the at least two target light beams; the second displacement stage is a fixed displacement stage, and the second displacement stage is used to fix the second part.

[0012] Optionally, it also includes: a fiber combiner;

[0013] The fiber combiner is located between the first optical fiber and the filtering structure, the first port of the fiber combiner is connected to the pump structure, the second port of the fiber combiner is connected to the first optical fiber, and the first light beam enters the first optical fiber through the first port and the second port of the fiber combiner in sequence;

[0014] The third port of the fiber combiner is connected to the filtering structure, the second light beam enters the filtering structure via the second port and the third port of the fiber combiner in sequence, the at least two target light beams enter the second optical fiber via the third port and the second port of the fiber combiner and the first optical fiber in sequence, and the output light beam is output via the first optical fiber, the second port and the third port of the fiber combiner and the filtering structure in sequence.

[0015] Optionally, the adjustment structure is located on a side of the circulator away from the first optical fiber, and the first translation stage and the second translation stage are arranged along a first direction, and the first direction is perpendicular to an arrangement direction of the adjustment structure and the circulator;

[0016] There is a preset distance between the first translation stage and the second translation stage, and the first translation stage drives the first portion to move along the first direction toward the second translation stage, and adjusts the bending degree of the first portion so that the first portion obtains the output light beam based on the at least two target light beams;

[0017] Wherein, when the distance between the first translation stage and the second translation stage is the preset distance, the portion of the first portion located between the first translation stage and the second translation stage is in a naturally straightened state.

[0018] Optionally, the at least two target light beams include a first target light beam and a second target light beam;

[0019] The filtering structure is an overlapping fiber Bragg grating.

[0020] Optionally, the pump structure is a semiconductor laser, and the wavelength of the first light beam is 793 nm;

[0021] The first optical fiber is a thulium-doped optical fiber, and the wavelength of the second light beam ranges from 1900 nm to 2100 nm, including end points;

[0022] The wavelength of the first target light beam is 2048.10 nm, and the wavelength of the second target light beam is 1940.64 nm.

[0023] Optionally, the preset distance between the first translation stage and the second translation stage is 10 cm;

[0024] The first translation stage drives the first part to move along the first direction toward the second translation stage, the distance between the first translation stage and the second translation stage is 10 cm to 6.6 cm, including the end value, and the output light beam is the first target light beam;

[0025] The first translation stage drives the first part to move along the first direction toward the second translation stage, the distance between the first translation stage and the second translation stage is 6.5-5.5 cm, including the end value, and the output light beam is the second target light beam.

[0026] Optionally, it further includes: a temperature controller, wherein the temperature controller is used to control the temperature of the filtering structure to adjust the wavelengths of the at least two target light beams.

[0027] A laser system comprises the laser with switchable output wavelength described in any one of the above embodiments.

[0028] A wind measuring radar comprises the laser with switchable output wavelength described in any one of the above embodiments.

[0029] Compared with the related art, the technical solution of the present application has the following beneficial effects:

[0030] The laser includes: a pump structure, a first optical fiber, a filtering structure and a wavelength switching structure, and the wavelength switching structure includes a second optical fiber and an adjustment structure. The first optical fiber generates a second optical beam based on the first optical beam emitted by the pump structure, the filtering structure filters the second optical beam to obtain at least two target optical beams, the second optical fiber obtains an output optical beam based on the at least two target optical beams, and the adjustment structure adjusts the bending degree of the second optical beam, and different bending degrees of the second optical fiber correspond to different wavelengths of the output optical beam. It can be seen that the laser can output laser beams of multiple wavelengths, and can also realize the wavelength selection of the output optical beam by the bending degree of the second optical fiber, and at the same time realize the wavelength selection of the output optical beam by the bending degree of the second optical fiber, and can also realize the flexible switching of output optical beams of different wavelengths, and has repeatability.

[0031] In addition, the laser can achieve wavelength selection of the output light beam by adjusting the degree of bending of the second optical fiber, that is, by adding an adjustment structure that can adjust the degree of bending of the second optical fiber. Compared with related technologies, the operation is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0033] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

[0034] Figure 1 It is a structural schematic diagram of an existing laser;

[0035] Figure 2 is a schematic diagram of the structure of another existing laser;

[0036] Figure 3 A schematic diagram of the structure of a laser with switchable output wavelength provided in this application;

[0037] Figure 4 A schematic diagram of the structure of another laser with switchable output wavelength provided in this application;

[0038] Figure 5 A schematic diagram of the structure of another switchable output wavelength laser provided in the present application;

[0039] Figure 6 is a schematic diagram of the bending of the first portion when the output light beam is the first target light beam;

[0040] Figure 7 is a schematic diagram of the bending of the first portion when the output light beam is the second target light beam;

[0041] Figure 8 A schematic diagram of the structure of another switchable output wavelength laser provided in the present application. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the embodiments in the present application. Obviously, the described embodiments are only embodiments of one area of ​​the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0043] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0044] As described in the background technology section, the current development trend of lasers requires that lasers can output lasers of multiple wavelengths, and the wavelengths of the output lasers can be selected.

[0045] For the above problems, in the related technologies, such as Figure 1 As shown, Figure 1 The figure is a schematic diagram of the structure of a laser in the related art, which consists of a fiber ring resonator and an optical filter module. The fiber ring resonator includes: a Thulium-doped Fiber Amplifier (TDFA), a 90 / 10 coupler, a polarization controller, a circulator (CIR), and a collimator. When the thulium-doped fiber in the thulium fiber amplifier is pumped by a 793nm laser, the thulium fiber amplifier can generate spontaneous radiation (ASE) light in the range of 1910~2020nm. After the ASE light passes through the coupler, 90% of the ASE light returns to the circulator and is further coupled to the optical filter module through the collimator.

[0046] The optical filtering module includes: a diffraction grating (Grating), a collimating lens (Lens), and a digital micromirror array (DMD). The collimating lens Lens is located between the diffraction grating Grating and the digital micromirror array DMD, and the controller (Remote control) is used to control the digital micromirror array DMD. The diffraction grating Grating and the digital micromirror array DMD are placed on the front and rear focal planes of the collimating lens Lens, respectively. The collimator irradiates the ASE light onto the diffraction grating Grating to generate first-order dispersion light in the horizontal direction. Subsequently, the ASE light is collimated by the collimating lens Lens and projected to different parts of the digital micromirror array DMD, thereby realizing the longitudinal mode selection and wavelength tuning of the laser. Finally, the selected band that enters the ring cavity through the collimator is amplified by the thulium-doped fiber amplifier, and after several cycles, laser output is generated.

[0047] However, for the above lasers, DMD chips are expensive and require high precision, which leads to high cost and complexity. In addition, as a MEMS device, the long-term stability and life of the mechanical components of DMD may not be as good as those of pure optical or all-fiber structures. Since the DMD chip contains movable micromirrors, it requires regular maintenance and calibration to ensure the accuracy of wavelength tuning and the stability of the laser. Based on the above, the laser will inevitably face problems such as high cost, short life and poor stability in real-world applications.

[0048] like Figure 2 As shown, Figure 2 is a schematic diagram of the structure of another laser in the related art. Figure 2 In the laser, LD is the pump source, FC (Fiber Combiner, FC for short) is the beam combiner, TDF (Thulium-Doped Fiber, TDF for short) is the thulium-doped fiber, CIR is the circulator, DI-PC is the polarization controller, SI-PM-FBG is the overlapped polarization-maintaining Bragg grating, and OC (Optical Coupler, OC for short) is the optical coupler. The laser uses a 793 nm laser diode with an output power of up to 12W, a beam combiner FC and a 5.9 m long Tm-doped 3+The double-clad fiber is an important component of the forward pump structure, providing sufficient gain for the laser operation in the ring cavity. SI-PM-FBG (overlapping polarization-maintaining Bragg grating) acts as a four-channel reflection filter, cooperating with the circulator (CIR) to ensure irreversible clockwise laser output, and DI-PC has low loss in the 2050 nm band, so DI-PC is selected to adjust the polarization state. The specific laser is injected from port 1 of the CIR and then reflected from port 2. The mode selection mechanism is realized by a composite double ring cavity composed of three optical couplers OC.

[0049] Based on the above, Figure 2 The laser is filtered by SI-PM-FBG, OC 1 , OC 2 and OC 3 The composite ring cavity composed of the optical couplers OC is used for mode selection, and the redundant longitudinal modes are filtered out. The wavelength selection and wavelength tuning are performed by adjusting the DI-PC. Specifically, the DI-PC is used to adjust the polarization state, and the wavelength selection and switching are achieved by introducing polarization-dependent loss and gain competition. By changing the setting of the DI-PC, it is possible to switch between four wavelengths to achieve single-wavelength, dual-wavelength, triple-wavelength and quad-wavelength output. However, the above-mentioned ring cavity laser including multiple optical couplers OC has a complicated structure and a long cavity length. It is not easy to integrate and miniaturize in industrial design, and is not conducive to large-scale production. In addition, the length of the composite ring cavity composed of OC needs to be strictly controlled. Therefore, the fault tolerance is low in the industrial production process and the manufacturing difficulty is high.

[0050] Based on the above, the present application provides a switchable output wavelength laser, such as Figure 3 As shown, Figure 3 This is a schematic structural diagram of a switchable output wavelength laser provided in the present application. The laser comprises: a pump structure 100 , a first optical fiber 200 , a filter structure 300 and a wavelength switching structure 400 .

[0051] The pump structure 100 is used to generate a first light beam, which may be referred to as pump light.

[0052] The first optical fiber 200 is connected to the pump structure 100 , receives the first light beam, generates a second light beam based on the first light beam, and transmits the second light beam to the filtering structure 300 , that is, the first optical fiber 200 can generate the second light beam based on the first light beam, and can also allow the second light beam to enter the filtering structure 300 .

[0053] The filtering structure 300 is used to filter the second light beam to obtain at least two target light beams, the wavelengths of the at least two target light beams are different, and the wavelengths of the at least two target light beams are within the wavelength range of the first light beam. In other words, the filtering structure 300 can filter the second light beam to obtain at least two laser beams with different wavelengths from the second light beam. It should be noted that the above-mentioned at least two target light beams are output light beams that the laser can output, that is, the laser can output at least two laser beams with different wavelengths, that is, the laser can output laser beams with multiple wavelengths.

[0054] The filtering structure 300 also transmits the at least two target light beams to the wavelength switching structure 400, which includes a second optical fiber 410 and an adjustment structure 420. The second optical fiber 410 receives at least two target light beams, and the second optical fiber 410 is used to obtain an output light beam based on the at least two target light beams, and the output light beam is one of the at least two target light beams. The adjustment structure 420 is used to adjust the bending degree of the second optical fiber 410. Different bending degrees of the second optical fiber 410 correspond to different wavelengths of the output light beam, that is, the bending degrees of the second optical fiber 410 are different, and the wavelengths of the output light beams obtained by the second optical fiber 410 based on the at least two target light beams are different. Then, the bending degree of the second optical fiber 410 can be changed by the adjustment structure 420 to obtain different output light beams. It should be noted that, due to the different degrees of bending of the second optical fiber 410, the optical losses of laser beams of different wavelengths transmitted therein are different. Therefore, the optical losses of at least two target light beams in the second optical fiber 410 can be controlled by adjusting the degree of bending of the second optical fiber 410, that is, the optical losses of at least two target light beams in the second optical fiber 410 are different, so as to realize the selection of the output light beam, and the output light beam is a light beam with smaller optical loss corresponding to the degree of bending of the second optical fiber 410 of the at least two target light beams.

[0055] As can be seen from the above, the laser can output laser beams of multiple wavelengths, and the wavelength of the output beam can be selected by the bending degree of the second optical fiber 410, which can meet the development trend of today's lasers requiring multi-wavelength output and selectable output beam wavelengths. At the same time, the wavelength of the output beam can be selected by the bending degree of the second optical fiber 410, which can realize flexible switching of output beams of different wavelengths, and has repeatability.

[0056] In addition, the laser can achieve wavelength selection of the output light beam by adjusting the bending degree of the second optical fiber 410, that is, by adding an adjustment structure that can adjust the bending degree of the second optical fiber 410. Compared with the related art, the operation is simple and the cost is low. For example, there is no need to add a DMD chip with high precision requirements and high price, nor is there a need for multiple optical couplers OC.

[0057] In addition, compared with lasers that include DMD chips, this laser does not have components such as movable microlenses that require regular maintenance and calibration, has better stability, is not affected by the service life of the DMD chip, and has a longer service life.

[0058] Compared with a laser including multiple optical couplers OC, the wavelength selection of the output light beam is realized by multiple optical couplers OC, which results in a complicated structure and a long cavity length of the laser. However, the present laser can realize the selection of the output wavelength only by bending the second optical fiber 410, which does not result in a complicated structure and a long cavity length of the laser, and does not affect the integration and miniaturization of the laser. On the contrary, it can be beneficial to the integration and miniaturization of the laser. At the same time, the structure is simple and easy to integrate into a more complex system. In addition, for the above-mentioned laser including multiple optical couplers OC, it is also necessary to strictly control the length of the composite ring cavity composed of OC, which is difficult to manufacture. However, the present laser only needs to add an adjustment structure that can adjust the bending degree of the second optical fiber 410, which is low in cost and low in manufacturing difficulty.

[0059] In summary, the laser with switchable output wavelength provided by the present application can output laser beams of multiple wavelengths, and the output wavelength can be flexibly switched. At the same time, compared with the related technologies, the laser also has the advantages of simple operation, low cost, long life, strong stability, low manufacturing difficulty, miniaturization and easy integration, and has broad application prospects.

[0060] In one embodiment of the present application, Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of a switchable output wavelength laser provided by the present application. For the wavelength switching structure 400, the wavelength switching structure 400 further includes a circulator 430. The first port 431 of the circulator 430 is connected to the first optical fiber 200, that is, the other end of the first optical fiber 200 other than the end connected to the pump structure 100 is connected to the first port 441 of the circulator 430. The second port 432 of the circulator 430 is connected to one end of the second optical fiber 410, so that the second optical fiber 410 and the first optical fiber 200 can be connected to each other through the first port 431 and the second port 432 of the circulator 430, and then at least two target light beams can enter the second optical fiber 410 through the first port 441 and the second port 442 of the circulator 430 in sequence after passing through the first optical fiber 200.

[0061] The third port 433 of the circulator 430 is connected to the other end of the second optical fiber 410, so that the output light beam can be output through the third port 433 and the first port 431 of the circulator 430. It should be noted that the first to third ports of the circulator 430 are arranged in a clockwise direction, and the light beam entering the circulator 430 can only be transmitted in a specified direction. For example, the light beam entering through the first port 431 of the circulator 430 can only be transmitted to the second port 432 through the single-mode optical fiber between the first port 431 and the second port 432, and emitted from the second port 432; the light beam entering through the second port 432 can only be transmitted to the third port 433 through the single-mode optical fiber between the second port 432 and the third port 433, and output from the third port 433; the light beam entering through the third port 433 can only be transmitted to the first port 431 through the single-mode optical fiber between the third port 433 and the first port 431, and emitted from the first port 431, so as to realize the directional transmission of the light beam entering the circulator 430.

[0062] Based on the above, the second optical fiber 410 may include a first portion 411 and a second portion 412 that are connected in sequence, that is, the second optical fiber 410 may include a first portion 411 and a second portion 412 that are connected end to end in sequence. One end of the first portion 411 is connected to the first port 431 of the circulator 430, and one end of the second portion 412 is connected to the third port 433 of the circulator 430.

[0063] The adjustment structure 420 includes a first displacement stage 421 and a second displacement stage 422. The first displacement stage 421 is a movable displacement stage. The first displacement stage 421 drives the first part 411 to move and adjusts the bending degree of the first part 411 so that the first part 411 can obtain an output beam based on at least two target beams. The second displacement stage 422 is a fixed displacement stage. The second displacement stage 422 is used to fix the second part 412 to avoid the second part 412 of the second optical fiber 410 from being deformed due to the first displacement stage 421 driving the first part 411 to move, resulting in a large optical loss of the output beam, thereby ensuring the efficient output of the output beam and thus ensuring the optical efficiency of the laser.

[0064] In one embodiment of the present application, Figure 5As shown, the laser further includes: a fiber combiner 500, the fiber combiner 500 is located between the first optical fiber 200 and the filter structure 300, specifically, the first port 501 of the fiber combiner 500 is connected to the pump structure 300, the second port 502 of the fiber combiner 500 is connected to the first optical fiber 200, and the first light beam enters the first optical fiber 200 through the first port 501 and the second port 502 of the fiber combiner 500 in sequence, that is, the first light beam generated by the pump structure 300 can enter the fiber combiner 500 through the first port 501 of the fiber combiner 500, and then enter the first optical fiber 200 through the second port 502 of the fiber combiner 500. Optionally, the fiber combiner 500 can be a (2+1)×1 multimode fiber combiner, and the core diameter can be 105μm.

[0065] The third port 503 of the fiber combiner 500 is connected to the filter structure 300. Based on this, the second light beam enters the filter structure 300 through the second port 502 and the third port 503 of the fiber combiner 500 in sequence. Specifically, after the first optical fiber 200 generates the second light beam based on the first light beam, the second light beam can enter the fiber combiner 500 through the second port 502 of the fiber combiner 500, and then enter the filter structure 300 through the third port 503 of the fiber combiner 500.

[0066] At least two target light beams enter the second optical fiber 410 in sequence through the third port 503 and the second port 502 of the optical fiber combiner 500 and the first optical fiber 200. Specifically, the filtering structure 300 obtains at least two target light beams based on the second light beam and reflects at least two target light beams, so that at least two target light beams can enter the optical fiber combiner 500 through the third port 503 of the optical fiber combiner 500, and then enter the first optical fiber 200 through the second port 502 of the optical fiber combiner 500, and enter the second optical fiber 410 through the first optical fiber 200.

[0067] The output light beam is outputted through the first optical fiber 200, the second port 502 and the third port 503 of the optical fiber combiner 500, and the filtering structure 300 in sequence. Specifically, after being outputted through the first port 401 of the circulator 430, the output light beam enters the first optical fiber 200, then enters the optical fiber combiner 500 through the second port 502 of the optical fiber combiner 500, and then enters the filtering structure 300 through the third port 503 of the optical fiber combiner 500, and finally is outputted through the output port Laser output connected to the filtering structure 300.

[0068] Based on the above, it can be known that the laser includes a fiber beam combiner 500, and the optical beam combiner 500 can efficiently transmit the laser beam to the next-level structure, which helps to reduce the optical loss of the laser and improve the optical efficiency of the laser.

[0069] In one embodiment of the present application, Figure 5As shown, the adjustment structure 420 is located on a side of the circulator 430 away from the first optical fiber 200 , and the first translation stage 421 and the second translation stage 422 are arranged along a first direction perpendicular to the arrangement direction of the adjustment structure 420 and the circulator 430 .

[0070] There is a preset distance between the first translation stage 421 and the second translation stage 422. The first translation stage 421 can drive the first portion 411 to move along the first direction toward the second translation stage 422, and adjust the bending degree of the first portion 411 to bend the second optical fiber 410 to a preset curvature, so that the first portion 411 of the second optical fiber 410 can obtain an output light beam based on at least two target light beams.

[0071] When the distance between the first translation stage 421 and the second translation stage 422 is a preset distance, the portion of the first portion 411 between the first translation stage 421 and the second translation stage 422 is in a naturally straightened state, so that the first translation stage 421 drives the first portion 411 to move along the first direction toward the second translation stage 422, and the bending degree of the first portion 411 can be adjusted, and then the second optical fiber 410 can be bent to a preset curvature.

[0072] As can be seen from the above, the laser controls the bending degree of the first part 411 of the second optical fiber 410 through the first displacement stage. Since the displacement stage can accurately control the movement accuracy, the bending degree of the first part 411 can be accurately controlled, and then the output wavelength selection and tuning can be accurately realized, which can be applied to application scenarios that require accurate control of the output wavelength. And since the movement of the displacement stage can be flexibly controlled, the laser can also flexibly realize the switching between output beams of different wavelengths, which is very important for application scenarios with multi-wavelength output.

[0073] Based on the above, in a specific embodiment of the present application, Figure 5 As shown, the second optical fiber 410 is in the shape of a rectangle, the adjustment structure 420 and the circulator 430 can be respectively located on two opposite sides of the rectangle formed by the second optical fiber 410, and the area where the first part 411 and the second part 412 of the second optical fiber 410 are connected is fixed to the second displacement stage 422, so that the first displacement stage 421 drives the first part 411 to move along the first direction toward the second displacement stage 422, and the shape of the second part 412 will not change, thereby ensuring the optical efficiency of the laser.

[0074] In one embodiment of the present application, the at least two target light beams include a first target light beam and a second target light beam, that is, the laser provided in the present application can output laser light beams of two wavelengths, but the present application is not limited to this. The at least two target light beams may also include laser light beams of at least three wavelengths, depending on the specific circumstances.

[0075] When the at least two target beams include laser beams of two wavelengths, namely, the first target beam and the second target beam, the filtering structure 300 is an overlapping fiber Bragg grating. The first filtering wavelength of the overlapping fiber Bragg grating is equal to the wavelength of the first target beam, and the second filtering wavelength is equal to the wavelength of the second target beam. The first target beam and the second target beam can be filtered out from the second beam to obtain the first target beam and the second target beam, that is, to obtain the at least two target beams.

[0076] Thulium-doped fiber lasers with a laser wavelength covering 1900nm~2100nm can be widely used in material processing, fiber optic sensing, spectroscopy, lidar systems, and Ho:YAG laser pumping, and therefore are attracting more and more attention. For the above-mentioned thulium-doped fiber lasers, the laser with a wavelength in the 2.05μm band has the advantage of an atmospheric transmittance of up to 70%, which is particularly suitable for free space applications such as free space optical communications. In addition, TDFL operating at a laser wavelength of 1.94μm seems to be more effective than Ho: YAG lasers in invasive surgeries (such as lithotripsy). Based on the above, a laser with an output wavelength of 2.05μm and 1.94μm and a switchable output wavelength becomes particularly important. Therefore, in one embodiment of the present application, the pump structure 100 may be a semiconductor laser (Laser Diode, LD for short), the output wavelength of the pump structure 100, i.e., the wavelength of the first light beam, may be 793 nm, the first optical fiber 200 may be a thulium-doped optical fiber, and the wavelength of the second light beam may range from 1900 nm to 2100 nm, including the end value. Based on the above, the first filtering wavelength of the filtering structure 300 may be 2048.10 nm, and the second filtering wavelength may be 1940.64 nm, and thus the wavelength of the first target light beam may be 2048.10 nm, and the wavelength of the second target light beam may be 1940.64 nm.

[0077] It should be noted that when the wavelength of the first light beam generated by the pump structure 100 is 793 nm, and the first optical fiber 200 is a thulium-doped optical fiber, the process of the first optical fiber 200 generating the second light beam based on the first light beam can be: after the first light beam enters the first optical fiber 200, the Tm in the first optical fiber 200 3+ The ions absorb the first beam and transition to the upper energy level. As the number of particles in the upper energy level increases, a population inversion occurs, causing the excited state Tm 3+ The ions will transition to the ground state energy level, generating radiation photons, which will be stimulated and amplified to produce a second light beam.

[0078] It should also be noted that, although in the above embodiment, the wavelength of the first target light beam is 2048.10 nm and the wavelength of the second target light beam is 1940.64 nm, the present application does not limit this and it depends on the specific circumstances.

[0079] In one embodiment of the present application, the pump structure 100 may be a commercial pump source from CSRayzer Opticaltechnology, with a maximum output power of 12 W. The first optical fiber 200 may be a thulium-doped optical fiber with a cladding absorption peak of 4.5 dB / m at 793 nm, and a core / cladding numerical aperture of 0.15 / 0.46, and a core and cladding diameter of 10 μm and 130 μm, respectively.

[0080] In one embodiment of the present application, the preset distance between the first translation stage 421 and the second translation stage 422 may be 10 cm, but the present application does not limit this, and the specific distance depends on the specific situation.

[0081] Based on the above, when the preset distance between the first translation stage 421 and the second translation stage 422 can be 10 cm, Figure 6 As shown, the first translation stage 421 drives the first portion 411 of the second optical fiber 410 to move along the first direction toward the second translation stage 422, and the distance between the first translation stage 421 and the second translation stage 422 is 10cm~6.6cm, including the endpoint value, and the output beam is the first target beam.

[0082] like Figure 7 As shown, the first translation stage 421 drives the first portion 411 of the second optical fiber 410 to move along the first direction toward the second translation stage 422, and the distance between the first translation stage 421 and the second translation stage 422 is 6.5~5.5cm, including the end value, and the output beam is the second target beam.

[0083] Based on the above, the distance between the first displacement stage 421 and the second displacement stage 422 is 10 cm to 6.6 cm, and the output beam is the first target beam. The distance between the first displacement stage 421 and the second displacement stage 422 is 6.5 to 5.5 cm, and the output beam is the second target beam, that is, as the bending degree of the first portion 411 of the second optical fiber 410 increases, the output beam changes from the first target beam to the second target beam. It should be noted that when the distance between the first displacement stage 421 and the second displacement stage 422 is 10 cm, the output beam is the first target beam, that is, when the first portion 411 of the second optical fiber 410 is not bent, the output beam is the first target beam. It should also be noted that when the distance between the first displacement stage 421 and the second displacement stage 422 is less than 5.5 cm, the bending degree of the first portion 411 of the second optical fiber 410 is too large, the optical loss of the first target beam and the second target beam is too large, and no laser beam is output.

[0084] In one embodiment of the present application, the laser further includes a temperature controller 600, which is disposed on the filter structure 300 and is used to control the temperature of the filter structure 300 to adjust the wavelengths of at least two target light beams and to fine-tune the wavelengths of at least two target light beams. For example, by using the temperature controller 600 to increase the temperature of the filter structure 300 from 50°C to 300°C, the wavelength range of the first target light beam may be 2048.44nm~2052.00nm, and the wavelength range of the second target light beam may be 1940.98nm~1944.30nm.

[0085] It should be noted that the resonator of the laser described in any of the above embodiments may be a linear cavity structure.

[0086] like Figure 8 As shown, Figure 8 A structural diagram of a switchable output wavelength laser provided in this application, Figure 8 In the figure, the semiconductor laser LD is the pump structure 100, the thulium-doped fiber TDF is the first optical fiber 200, the overlapping fiber Bragg grating SI-FBG is the filter structure 300, the circulator CIR is the circulator 430, and the combiner FC is the fiber combiner 500. Based on the above, the components such as the pump structure 100, the circulator 430 and the fiber combiner 500 in the laser can all be commercial products, which contributes to the reliability and reproducibility of the laser, and also facilitates the maintenance of the laser and the replacement of components, and has strong practicality.

[0087] The present application also provides a laser system, which includes the switchable output wavelength laser described in any one of the above embodiments.

[0088] The present application also provides a wind measuring radar, which includes the switchable output wavelength laser described in any one of the above embodiments.

[0089] In this specification, each embodiment is described in a progressive, parallel, or progressive and parallel manner. Each embodiment focuses on the differences from other embodiments, and the same or similar areas between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method area description.

[0090] It should be noted that in the description of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. When a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0091] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0092] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A switchable output wavelength laser, characterized in that: include: A pump structure, a first optical fiber, a filtering structure and a wavelength switching structure; The pump structure is used to generate a first light beam; The first optical fiber receives the first light beam, generates a second light beam based on the first light beam, and transmits the second light beam to the filtering structure; The filtering structure filters the second light beam to obtain at least two target light beams, the wavelengths of the at least two target light beams are different, and the wavelengths of the at least two target light beams are within the wavelength range of the second light beam; The filtering structure transmits the at least two target light beams to the wavelength switching structure, which includes a second optical fiber and an adjustment structure. The second optical fiber obtains an output light beam based on the at least two target light beams, and the output light beam is one of the at least two target light beams. The adjustment structure is used to adjust the bending degree of the second optical fiber, and different bending degrees of the second optical fiber correspond to different wavelengths of the output light beam.

2. The switchable output wavelength laser according to claim 1, characterized in that: The wavelength switching structure further comprises a circulator, wherein a first port of the circulator is connected to the first optical fiber, a second port of the circulator is connected to one end of the second optical fiber, and a third port of the circulator is connected to the other end of the second optical fiber, the at least two target light beams sequentially enter the second optical fiber through the first port and the second port of the circulator, and the output light beam is sequentially output through the third port and the first port of the circulator; The second optical fiber includes a first part and a second part that are connected, and one end of the first part is connected to the first port of the circulator, and one end of the second part is connected to the third port of the circulator; the adjustment structure includes a first displacement stage and a second displacement stage, the first displacement stage is a movable displacement stage, the first displacement stage drives the first part to move, and adjusts the bending degree of the first part so that the first part obtains the output light beam based on the at least two target light beams; the second displacement stage is a fixed displacement stage, and the second displacement stage is used to fix the second part.

3. The switchable output wavelength laser according to claim 2, characterized in that: Also includes: Fiber combiner; The fiber combiner is located between the first optical fiber and the filtering structure, the first port of the fiber combiner is connected to the pump structure, the second port of the fiber combiner is connected to the first optical fiber, and the first light beam enters the first optical fiber through the first port and the second port of the fiber combiner in sequence; The third port of the fiber combiner is connected to the filtering structure, the second light beam enters the filtering structure via the second port and the third port of the fiber combiner in sequence, the at least two target light beams enter the second optical fiber via the third port and the second port of the fiber combiner and the first optical fiber in sequence, and the output light beam is output via the first optical fiber, the second port and the third port of the fiber combiner and the filtering structure in sequence.

4. The switchable output wavelength laser according to claim 3, characterized in that: The adjustment structure is located at a side of the circulator away from the first optical fiber, and the first translation stage and the second translation stage are arranged along a first direction, and the first direction is perpendicular to an arrangement direction of the adjustment structure and the circulator; There is a preset distance between the first translation stage and the second translation stage, and the first translation stage drives the first portion to move toward the second translation stage along the first direction, and adjusts the bending degree of the first portion so that the first portion obtains the output light beam based on the at least two target light beams; Wherein, when the distance between the first translation stage and the second translation stage is the preset distance, the portion of the first portion located between the first translation stage and the second translation stage is in a naturally straightened state.

5. The switchable output wavelength laser according to claim 4, characterized in that: The at least two target light beams include a first target light beam and a second target light beam; The filtering structure is an overlapping fiber Bragg grating.

6. The switchable output wavelength laser according to claim 5, characterized in that: The pump structure is a semiconductor laser, and the wavelength of the first light beam is 793nm; The first optical fiber is a thulium-doped optical fiber, and the wavelength of the second light beam ranges from 1900 nm to 2100 nm, including end points; The wavelength of the first target light beam is 2048.10 nm, and the wavelength of the second target light beam is 1940.64 nm.

7. The switchable output wavelength laser according to claim 5, characterized in that: The preset distance between the first translation stage and the second translation stage is 10 cm; The first translation stage drives the first part to move along the first direction toward the second translation stage, the distance between the first translation stage and the second translation stage is 10 cm to 6.6 cm, including the end value, and the output light beam is the first target light beam; The first translation stage drives the first part to move along the first direction toward the second translation stage, the distance between the first translation stage and the second translation stage is 6.5-5.5 cm, including the end value, and the output light beam is the second target light beam.

8. The switchable output wavelength laser according to claim 1, characterized in that: Also includes: A temperature controller is used to control the temperature of the filter structure to adjust the wavelengths of the at least two target light beams.

9. A laser system, characterized in that: A laser with switchable output wavelength comprising the laser of any one of claims 1-8.

10. A wind measurement radar, characterized in that: A laser with switchable output wavelength comprising the laser of any one of claims 1-8.

Images