Single-frequency fiber laser with frequency stabilization unit

Abstract

The utility model discloses a single-frequency fiber laser with a frequency stabilization unit, and relates to the technical field of lasers. Comprising a pumping source, a first wavelength division multiplexer, an optical resonant cavity, a second wavelength division multiplexer, a light splitting assembly, a first fiber grating, a variable optical attenuator, a first optical detector, a second optical detector, a PID controller and piezoelectric ceramics. The pumping source, the first wavelength division multiplexer, the optical resonant cavity, the second wavelength division multiplexer and the light splitting assembly are connected in sequence; a first light output port of the light splitting assembly, the first fiber grating, the first light detector and the PID controller are sequentially connected, a second light output port of the light splitting assembly, the variable optical attenuator, the second light detector and the PID controller are sequentially connected, the PID controller is further connected with the piezoelectric ceramic, and one end of the optical resonant cavity is fixedly connected with the piezoelectric ceramic. The single-frequency fiber laser with the frequency stabilization unit can reduce the size, weight and cost of a product while realizing a frequency stabilization function.

Description

Technical Field

[0001] The utility model belongs to the technical field of lasers, and in particular relates to a single-frequency optical fiber laser with a frequency stabilizing unit. Background Art

[0002] Single-frequency fiber lasers have great application value in coherent optical communications, Doppler wind radar, cold atom physics experiments, gravitational wave detection, quantum optics and other fields. More and more application scenarios require single-frequency fiber lasers to have higher frequency stability. Current passive frequency stabilization, such as stabilizing the power supply, reducing power supply noise, and constant temperature control, can improve the frequency stability of single-frequency fiber lasers, but experiments show that in order to obtain a high level of frequency stability, further active frequency stabilization measures are required.

[0003] Among the existing single-frequency fiber lasers, the mainstream active frequency stabilization method, the key technology of which is the offset frequency locking technology. The traditional offset frequency locking technology requires the installation of separate components such as the Fabry-Perot interferometer FPI and the molecular absorption spectrum module as frequency discrimination modules in the single-frequency fiber laser. As a result, the single-frequency fiber laser has large structural size, high weight, and cannot be moved at will. As a result, this solution can only be used in laboratories or specific environments, and it is difficult to integrate and develop it into a separate product application. Utility Model Content

[0004] The purpose of the utility model is to provide a single-frequency fiber laser with a frequency stabilizing unit to solve the above problems existing in the prior art.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A single-frequency fiber laser with a frequency stabilization unit comprises: a pump source, a first wavelength division multiplexer, an optical resonant cavity, a second wavelength division multiplexer, a light splitting component, a first fiber grating, a variable optical attenuator, a first light detector, a second light detector, a PID controller and piezoelectric ceramics;

[0007] The pump source, the first wavelength division multiplexer, the optical resonant cavity, the second wavelength division multiplexer and the light splitting component are connected in sequence;

[0008] The light splitting component comprises a first light output port and a second light output port, the first light output port, the first fiber grating, the first light detector and the PID controller are connected in sequence, the second light output port, the variable optical attenuator, the second light detector and the PID controller are connected in sequence, the PID controller is also connected to the piezoelectric ceramic, and one end of the optical resonant cavity is fixedly connected to the piezoelectric ceramic;

[0009] The output power of the first optical output port is the same as that of the second optical output port, and the insertion loss of the laser light of a specified frequency passing through the first fiber grating is the same as the insertion loss of the variable optical attenuator.

[0010] Based on the above disclosed content, the single-frequency fiber laser with a frequency stabilization unit provided by the utility model is provided with a pump source, a first wavelength division multiplexer, an optical resonant cavity, a second wavelength division multiplexer, a light splitting component, a first fiber grating, a variable optical attenuator, a first light detector, a second light detector, a PID controller and a piezoelectric ceramic. The pump source, the first wavelength division multiplexer, the optical resonant cavity, the second wavelength division multiplexer and the light splitting component are connected in sequence; the light splitting component includes a first light output port and a second light output port, the first light output port, the first fiber grating, the first light detector and the PID controller are connected in sequence, the second light output port, the variable optical attenuator, the second light detector and the PID controller are connected in sequence, the PID controller is also connected to the piezoelectric ceramic, and one end of the optical resonant cavity is fixedly connected to the piezoelectric ceramic. In this way, the frequency stabilization function of the single-frequency fiber laser with a frequency stabilization unit can be achieved by improving the structure of the single-frequency fiber laser with a frequency stabilization unit, without adding separate components such as the Fabry-Perot interferometer FPI and the molecular absorption spectrum module as a frequency discrimination module. Compared with the prior art, the frequency stabilization function can be integrated into the single-frequency fiber laser with a frequency stabilization unit, while achieving the frequency stabilization function, reducing the size, weight and cost of the product, and making it convenient to move the single-frequency fiber laser with a frequency stabilization unit for application in different scenarios.

[0011] In one possible design, the doped optical fiber is doped with at least one element selected from the group consisting of ytterbium, erbium, thulium, holmium and neodymium.

[0012] In one possible design, the optical resonant cavity includes a second fiber grating, a third fiber grating and a doped fiber, and the first wavelength division multiplexer, the second fiber grating, the doped fiber, the third fiber grating and the second wavelength division multiplexer are connected in sequence.

[0013] In one possible design, the optical splitter component includes a first optical splitter and a second optical splitter, the second optical splitter includes the first optical output port and the second optical output port, the first optical splitter includes a third optical output port and a fourth optical output port, the second wavelength division multiplexer is connected to the optical input port of the first optical splitter, the third optical output port is used to output laser light to the outside, and the fourth optical output port is connected to the optical input port of the second optical splitter.

[0014] In a possible design, the single-frequency fiber laser with a frequency stabilization unit also includes a temperature-controlled metal block, one side of which is provided with a first through groove and a second through groove, the optical resonant cavity is arranged in the first through groove, the first fiber grating is arranged in the second through groove, and the piezoelectric ceramic is arranged on one side of the temperature-controlled metal block adjacent to the first through groove and fixedly connected to the optical resonant cavity.

[0015] In a possible design, the single-frequency fiber laser with frequency stabilization function further includes a semiconductor refrigerator, and the semiconductor refrigerator is arranged on a side of the temperature-controlled metal block away from the first through groove.

[0016] In a possible design, the temperature-controlled metal block is an aluminum block.

[0017] In a possible design, the first through slot is arranged in parallel with the second through slot.

[0018] In a possible design, the second wavelength division multiplexer includes a first output end and a second output end, the first output end is connected to the light splitting component, and the second output end is used to output residual pump light to the outside.

[0019] Beneficial effects:

[0020] The single-frequency fiber laser with a frequency stabilization unit provided by the utility model can realize the frequency stabilization function of the single-frequency fiber laser with a frequency stabilization unit by improving the structure of the single-frequency fiber laser with a frequency stabilization unit, without adding separate components such as a Fabry-Perot interferometer FPI and a molecular absorption spectrum line module as a frequency discrimination module. Compared with the prior art, the frequency stabilization function can be integrated into the single-frequency fiber laser with a frequency stabilization unit, and while realizing the frequency stabilization function, the size, weight and cost of the product can be reduced, and the single-frequency fiber laser with a frequency stabilization unit can be conveniently moved so as to be applied to different scenarios, thereby facilitating applicability and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a single-frequency fiber laser with a frequency stabilization unit provided by the utility model.

[0022] icon:

[0023] 1-pump source; 2-first wavelength division multiplexer; 3-optical resonant cavity; 31-second fiber grating; 32-third fiber grating; 33-doped fiber; 4-second wavelength division multiplexer; 5-spectral splitting component; 51-first spectrometer; 52-second spectrometer; 6-first fiber grating; 7-variable optical attenuator; 8-first light detector; 9-second light detector; 10-PID controller; 11-piezoelectric ceramic. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the utility model will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the utility model, but does not constitute a limitation of the utility model.

[0025] It should be understood that although the terms first, second, etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another unit. For example, a first unit can be referred to as a second unit, and similarly, a second unit can be referred to as a first unit without departing from the scope of the exemplary embodiments of the present utility model.

[0026] In order to achieve frequency stabilization while reducing the size and weight of the product so that it can be used in different scenarios, an embodiment of the present application provides a single-frequency fiber laser with a frequency stabilization unit. The single-frequency fiber laser with a frequency stabilization unit can integrate the frequency stabilization function on the single-frequency fiber laser with the frequency stabilization unit. While achieving the frequency stabilization function, the size, weight and cost of the product are reduced, and it is convenient to move it for application in different scenarios.

[0027] See also Figure 1 The present embodiment provides a single-frequency fiber laser with a frequency stabilization unit, which includes a pump source 1, a first wavelength division multiplexer 2, an optical resonant cavity 3, a second wavelength division multiplexer 4, a light splitting component 5, a first fiber grating 6, a variable optical attenuator 7, a first light detector 8, a second light detector 9, a PID controller 10 and a piezoelectric ceramic 11.

[0028] Among them, the pump source 1, the first wavelength division multiplexer 2, the optical resonant cavity 3, the second wavelength division multiplexer 4 and the splitter component 5 are connected in sequence; the splitter component 5 includes a first optical output port and a second optical output port, the first optical output port, the first fiber grating 6, the first light detector 8 and the PID controller 10 are connected in sequence, the second optical output port, the variable optical attenuator 7, the second light detector 9 and the PID controller 10 are connected in sequence, the PID controller 10 is also connected to the piezoelectric ceramic 11, and one end of the optical resonant cavity 3 is fixedly connected to one end of the piezoelectric ceramic 11; the output power of the first optical output port is the same as that of the second optical output port, and the insertion loss of the laser of the specified frequency passing through the first fiber grating 6 is the same as the insertion loss of the variable optical attenuator 7.

[0029] The pump source 1 is used to generate pump light, and the first wavelength division multiplexer 2 is used to couple the pump light generated by the pump source 1 to the optical resonant cavity 3. The optical resonant cavity 3 oscillates under the condition of satisfying positive feedback to generate laser light of a certain wavelength. Specifically, the optical resonant cavity 3 includes a second fiber grating 31, a third fiber grating 32 and a doped fiber 33. The first wavelength division multiplexer 2, the second fiber grating 31, the doped fiber 33, the third fiber grating 32 and the second wavelength division multiplexer 4 are connected in sequence. The doped fiber 33 is doped with at least one element of ytterbium, erbium, thulium, holmium and neodymium.

[0030] The second wavelength division multiplexer 4 includes a first output end and a second output end. The first output end is connected to the light splitting component 5 and is used to input the laser light generated by the optical resonant cavity 3 to the light splitting component 5. The second output end is used to output the residual pump light.

[0031] The optical splitter component 5 has a first optical output port and a second optical output port with the same output power, so that the first optical output port and the second optical output port output lasers with the same power, a part of which enters the second optical detector 9 through the variable optical attenuator 7 as a reference light, and the other part enters the first optical detector 8 through the first fiber grating 6 as a frequency discrimination element. Specifically, the optical splitter component 5 includes a first optical splitter 51 and a second optical splitter 52, wherein the second optical splitter 52 includes the first optical output port and the second optical output port, the first optical splitter 51 includes a third optical output port and a fourth optical output port, the second wavelength division multiplexer 4 is connected to the optical input port of the first optical splitter 51, the third optical output port is used to output laser light to the outside, and the fourth optical output port is connected to the optical input port of the second optical splitter 52.

[0032] When selecting the first fiber grating 6, it is necessary to ensure that the frequency of the laser generated by the oscillation of the optical resonant cavity 3 is near the maximum slope of one side of the transmission spectrum of the first fiber grating 6 (i.e. near the middle position of the transmission spectrum, where the frequency discrimination function of the fiber grating is most sensitive).

[0033] In the embodiment of the present application, the insertion loss of the laser of the specified frequency passing through the first fiber grating 6 is the same as the insertion loss of the variable optical attenuator 7, wherein the specified frequency is the frequency required for stabilization of the single-frequency fiber laser with a frequency stabilization unit.

[0034] The PID controller 10 is connected to the first photodetector 8, the second photodetector 9 and the piezoelectric ceramic 11 respectively. The PID controller 10 is used to obtain the voltage output by the first photodetector 8 and the second photodetector 9, and generate a control signal based on the voltage difference output by the first photodetector 8 and the second photodetector 9 to control the expansion and contraction of the piezoelectric ceramic 11, thereby adjusting the cavity length of the optical resonant cavity 3 fixedly connected to the piezoelectric ceramic 11, and then adjusting the laser frequency output by the single-frequency fiber laser with a frequency stabilization unit to achieve the function of frequency stabilization.

[0035] Specifically, due to the transmission spectrum of the first fiber grating 6, inputting lasers of different frequencies into the first fiber grating 6 will result in different power attenuation of the first fiber grating 6, that is, different powers of the laser output from the first fiber grating 6. If the frequency of the laser input into the first fiber grating 6 is exactly the specified frequency, that is, the frequency that needs to be stabilized is output, the insertion loss of the laser passing through the first fiber grating 6 and the variable optical attenuator 7 is exactly the same, and the voltage difference output by the first light detector 8 and the second light detector 9 is 0. At this time, the PID controller 10 does not control the piezoelectric ceramic 11, the cavity length of the optical resonant cavity 3 fixedly connected to the piezoelectric ceramic 11 remains unchanged, and the third optical output port outputs a laser with a stable frequency.

[0036] If the laser frequency input to the first fiber grating 6 is not the frequency that needs to be stabilized, the insertion loss of the laser passing through the first fiber grating 6 and the variable optical attenuator 7 is different, and the voltage difference output by the first light detector 8 and the second light detector 9 is not 0. At this time, the PID controller 10 generates an adjustment signal to control the expansion and contraction of the piezoelectric ceramic 11, thereby adjusting the cavity length of the optical resonant cavity 3 fixedly connected to the piezoelectric ceramic 11 to adjust the frequency of the output laser until the frequency of the output laser reaches the frequency that needs to be stabilized, and the control of the piezoelectric ceramic 11 is stopped. At this time, the cavity length of the optical resonant cavity 3 fixedly connected to the piezoelectric ceramic 11 remains unchanged, and the third optical output port outputs laser light with a stable frequency.

[0037] One end of the optical resonant cavity 3 is fixedly connected to the piezoelectric ceramic 11 , which may be but is not limited to bonding or hot-melt connection. In the embodiment of the present application, one end of the optical resonant cavity 3 is bonded to the piezoelectric ceramic 11 .

[0038] In one or more embodiments, the single-frequency fiber laser with a frequency stabilization unit further includes a temperature-controlled metal block and a semiconductor refrigerator, one side of the temperature-controlled metal block is provided with a first through groove and a second through groove, the optical resonant cavity 3 is provided in the first through groove, the first fiber grating 6 is provided in the second through groove, and the piezoelectric ceramic 11 is provided at a side of the temperature-controlled metal block adjacent to the first through groove and fixedly connected to the optical resonant cavity 3. The semiconductor refrigerator is provided on a side of the temperature-controlled metal block away from the first through groove.

[0039] The cooling effect can be achieved by setting a semiconductor refrigerator. By setting a first through groove and a second through groove on the temperature-controlled metal block, and setting the optical resonant cavity 3 in the first through groove, and setting the first fiber grating 6 in the second through groove, the beneficial effect is that the temperatures of the first fiber grating 6, the second fiber grating 31 and the third fiber grating 32 can be kept consistent, and the drift direction and drift amount of the center frequency of the three fiber gratings will also be consistent (the center frequency of the fiber grating will drift with the ambient temperature). In this way, the frequency of the output laser can be kept always near the maximum slope on one side of the transmission spectrum of the first fiber grating 6. It is known that the output frequency is determined by the center frequency of the fiber grating 1 / 2, so the output laser frequency can be kept stable at all times, and the frequency stabilization function can be more effectively achieved.

[0040] In the embodiment of the present application, the first through slot is arranged in parallel with the second through slot, and the temperature control metal block is an aluminum block. It can be understood that in some other embodiments, the temperature control metal block can also be made of other materials, such as a copper block.

[0041] In summary, the single-frequency fiber laser with a frequency stabilization unit provided by the utility model is provided with a pump source 1, a first wavelength division multiplexer 2, an optical resonant cavity 3, a second wavelength division multiplexer 4, a splitter component 5, a first fiber grating 6, a variable optical attenuator 7, a first light detector 8, a second light detector 9, a PID controller 10 and a piezoelectric ceramic 11. The pump source 1, the first wavelength division multiplexer 2, the optical resonant cavity 3, the second wavelength division multiplexer 4 and the splitter component 5 are connected in sequence; the splitter component 5 includes a first light output port and a second light output port, the first light output port, the first fiber grating 6, the first light detector 8 and the PID controller 10 are connected in sequence, the second light output port, the variable optical attenuator 7, the second light detector 9 and the PID controller 10 are connected in sequence, the PID controller 10 is also connected to the piezoelectric ceramic 11, and one end of the optical resonant cavity 3 is fixedly connected to one end of the piezoelectric ceramic 11. In this way, the frequency stabilization function of the single-frequency fiber laser with a frequency stabilization unit can be realized by improving the structure of the single-frequency fiber laser with a frequency stabilization unit, without adding separate components such as the Fabry-Perot interferometer FPI and the molecular absorption spectrum module as a frequency discrimination module. Compared with the prior art, the frequency stabilization function can be integrated into the single-frequency fiber laser with a frequency stabilization unit, while realizing the frequency stabilization function, reducing the size, weight and cost of the product, and conveniently moving the single-frequency fiber laser with a frequency stabilization unit for application in different scenarios, which is convenient for application and promotion. At the same time, by setting a temperature-controlled metal block, the first fiber grating 6, the second fiber grating 31 and the third fiber grating 32 are all set on the temperature-controlled metal block, so that the output laser frequency can always be kept near the maximum slope on one side of the transmission spectrum of the fiber grating 6, and the frequency stabilization function can be more effectively realized.

[0042] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A single-frequency fiber laser with a frequency stabilization unit, characterized in that: include: A pump source, a first wavelength division multiplexer, an optical resonant cavity, a second wavelength division multiplexer, a light splitting component, a first fiber grating, a variable optical attenuator, a first light detector, a second light detector, a PID controller and piezoelectric ceramics; The pump source, the first wavelength division multiplexer, the optical resonant cavity, the second wavelength division multiplexer and the light splitting component are connected in sequence; The light splitting component comprises a first light output port and a second light output port, the first light output port, the first fiber grating, the first light detector and the PID controller are connected in sequence, the second light output port, the variable optical attenuator, the second light detector and the PID controller are connected in sequence, the PID controller is also connected to the piezoelectric ceramic, and one end of the optical resonant cavity is fixedly connected to the piezoelectric ceramic; The output power of the first optical output port is the same as that of the second optical output port, and the insertion loss of the laser light of a specified frequency passing through the first fiber grating is the same as the insertion loss of the variable optical attenuator.

2. The single-frequency fiber laser with a frequency stabilization unit according to claim 1, characterized in that: The optical resonant cavity includes a second fiber grating, a third fiber grating and a doped fiber, and the first wavelength division multiplexer, the second fiber grating, the doped fiber, the third fiber grating and the second wavelength division multiplexer are connected in sequence.

3. The single-frequency fiber laser with a frequency stabilization unit according to claim 2, characterized in that: The doped optical fiber is doped with at least one element selected from the group consisting of ytterbium, erbium, thulium, holmium and neodymium.

4. The single-frequency fiber laser with a frequency stabilization unit according to claim 1, characterized in that: The optical splitter assembly includes a first optical splitter and a second optical splitter, the second optical splitter includes the first optical output port and the second optical output port, the first optical splitter includes a third optical output port and a fourth optical output port, the second wavelength division multiplexer is connected to the optical input port of the first optical splitter, the third optical output port is used to output laser light to the outside, and the fourth optical output port is connected to the optical input port of the second optical splitter.

5. The single-frequency fiber laser with a frequency stabilization unit according to claim 1, characterized in that: It also includes a temperature-controlled metal block, one side of which is provided with a first through groove and a second through groove, the optical resonant cavity is arranged in the first through groove, the first fiber grating is arranged in the second through groove, and the piezoelectric ceramic is arranged on one side of the temperature-controlled metal block near the first through groove and fixedly connected to the optical resonant cavity.

6. The single-frequency fiber laser with a frequency stabilization unit according to claim 5, characterized in that: It also includes a semiconductor refrigerator, which is arranged on a side of the temperature-control metal block away from the first through groove.

7. The single-frequency fiber laser with a frequency stabilization unit according to claim 6, characterized in that: The temperature control metal block is an aluminum block.

8. The single-frequency fiber laser with a frequency stabilization unit according to claim 5, characterized in that: The first through slot is arranged in parallel with the second through slot.

9. The single-frequency fiber laser with a frequency stabilization unit according to claim 1, characterized in that: The second wavelength division multiplexer includes a first output end and a second output end, the first output end is connected to the light splitting component, and the second output end is used to output residual pump light to the outside.

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