阅读说明：本技术 一种冷原子干涉仪单激光器光源系统 (Cold atom interferometer single laser light source system ) 是由 杨俊� 王国超 朱凌晓 颜树华 郭熙业 王亚宁 吕梦洁 徐东洋 贾爱爱 李期学 于 2020-08-13 设计创作，主要内容包括：本发明提供了一种冷原子干涉仪单激光器光源系统,包括：参考光路模块和光学移频模块；参考光路模块包括窄带宽激光器和稳频模块；所述光学移频模块包括第一电光调制器和第一窄带宽光纤滤波器,所述第一电光调制器和所述第一窄带宽光纤滤波器通过光纤连接；所述第一电光调制器与所述激光器光纤连接；所述第一电光调制器接收激光源的初始光,通过预设频率的调制信号对所述初始光进行调制,产生预设频率的边带；所述第一窄带宽光纤滤波器对所述电光调制器输出的光信号进行滤波,得到+1阶边带的移频光；所述移频光用于调制得到冷原子于涉仪的测控光。该激光系统低成本、低功耗、可移动、体积小,且可消除拉曼边带效应。(The invention provides a cold atom interferometer single laser light source system, comprising: the device comprises a reference light path module and an optical frequency shift module; the reference optical path module comprises a narrow bandwidth laser and a frequency stabilization module; the optical frequency shift module comprises a first electro-optical modulator and a first narrow-bandwidth optical fiber filter, and the first electro-optical modulator and the first narrow-bandwidth optical fiber filter are connected through an optical fiber; the first electro-optical modulator is connected with the laser optical fiber; the first electro-optical modulator receives initial light of a laser source, modulates the initial light through a modulation signal with a preset frequency, and generates a sideband with the preset frequency; the first narrow-bandwidth optical fiber filter filters an optical signal output by the electro-optical modulator to obtain frequency shift light of a +1 order sideband; and the frequency shift light is used for modulating to obtain the measurement and control light of the cold atom interferometer. The laser system has low cost, low power consumption, mobility and small volume, and can eliminate the Raman sideband effect.)

1. A cold atom interferometer single laser light source system, comprising:

the device comprises a reference light path module and an optical frequency shift module;

the reference optical path module comprises a laser and a frequency stabilization module, and is used for providing a frequency-stabilized and narrow-bandwidth laser source;

the optical frequency shift module comprises a first electro-optical modulator and a first narrow-bandwidth optical fiber filter, and the first electro-optical modulator and the first narrow-bandwidth optical fiber filter are connected through an optical fiber; the first electro-optical modulator is connected with the laser optical fiber;

the first electro-optic modulator receives initial light generated by a laser, and modulates the initial light through a modulation signal with a preset frequency to generate a sideband with the preset frequency;

the first narrow-bandwidth optical fiber filter filters an optical signal output by the electro-optical modulator to obtain frequency shift light of a +1 order sideband; and the frequency shift light is used for modulating to obtain the measurement and control light of the cold atom interferometer.

2. The cold atom interferometer single laser light source system of claim 1, wherein the reference light path module further comprises a beam splitter, the beam splitter is disposed between the laser and the frequency stabilization module, one path of light output by the beam splitter is input to the frequency stabilization module, and the other path of light is input to the first electro-optical modulator.

3. A cold atom interferometer single laser light source system as claimed in claim 2, wherein said beam splitter also outputs a path of blown light; the blown light is controlled by an optical control switch.

4. The cold atom interferometer single laser light source system of claim 1, further comprising a single sideband modulation module, wherein the optical frequency shift module is connected with the single sideband modulation module through an optical fiber.

5. A cold atom interferometer single laser light source system as claimed in claim 4, wherein said single sideband modulation module comprises a second electro-optical modulator and a second narrow bandwidth fiber filter; the second electro-optic modulator and the second narrow bandwidth fiber filter are connected by an optical fiber.

6. A cold atom interferometer single laser light source system as claimed in claim 5, wherein the first and second narrow bandwidth fiber filters each comprise an optical circulator, a grating, an input port, a reflective output port and a transmissive output port, the optical circulator being connected to the input port, the transmissive output port and the reflective output port respectively, the grating being disposed between the optical circulator and the transmissive output port.

7. A cold atom interferometer single laser light source system as claimed in claim 5, further comprising an optical amplifier and an acousto-optical modulator; and the single-side band modulation module is sequentially connected with the optical amplifier and the acoustic-optical modulator through optical fibers.

8. The system of claim 7, further comprising a power control module electrically connected to the acousto-optic modulator via an instantaneous power measurement and control module for outputting light with stable total power.

9. The system of claim 7, further comprising a power control module for voltage modulating the electro-optical modulator by the local oscillator for outputting light with stable power ratio.

10. The cold atom interferometer single laser light source system of claim 1, wherein the laser is a 780nm laser or a 1560nm laser;

when the laser is 1560nm, the reference light and the measurement and control light output by the reference light path module and the optical frequency shift module need to be subjected to optical frequency doubling through the optical fiber amplifier and the frequency doubling crystal, and then the wavelength is converted into 780 nm.

Technical Field

The invention belongs to the field of quantum precision measurement based on cold atom interference technology, and particularly relates to a single laser light source system of a cold atom interferometer.

Background

The atomic interference technology takes atomic substance wave characteristics as a research means, and is widely applied to the field of precision measurement, such as physical quantity measurement of high-precision rotation angular velocity, gravity acceleration, universal gravitational constant and the like. In the cold atom interferometer, cold atoms are used as a measurement sensitive medium, and compared with other measurement means such as optical interference, the cold atoms have the advantages of long free evolution time, small atomic group velocity distribution, short de broglie wavelength, large relative mass and the like, so that the cold atom interferometer has better coherence in space and velocity distribution, and has higher measurement sensitivity, precision and long-term stability.

In the cold atom interference process, the target cold atom group is obtained through atom laser cooling and trapping, speed selection and initial state preparation, interference is carried out through atom beam splitting, reflection and beam combination, interference fringes are obtained through final state detection, and relevant measurement information is extracted. In the process, light with different frequencies and powers, such as cooling light, back pumping light, blowing light, Raman light, detecting light and the like, is required to be provided by a laser light source system. In order to meet the practical, commercial and movable measurement requirements of the atomic interferometer, a compact laser system with simple structure, small volume, low power consumption, good stability, high integration degree and low cost needs to be designed. In the past, most of laser light source systems are built on an optical platform in a laboratory, and the requirements of carrying and field practicability of a movable cold atom interferometer cannot be met. In recent years, many cold atom interferometer groups have been studied in order to realize an engineering modularized laser system. At present, a modularized integrated laser light source system can be divided into two schemes, one is a multi-laser light source system, and the other is a single-laser light source system.

The multi-laser light source system generally adopts a reference laser to lock on a reference frequency through a frequency stabilization method, and then uses an optical phase-locked loop technology to lock a plurality of lasers on the reference laser simultaneously or in a time-sharing manner, so as to generate laser output with various frequencies. Typical multi-laser systems such as the high reliability multi-laser system developed by the university of germany Hongbu for space cold atom interferometers, (SchkolnikV, helmig O, wenzlawkia, et al. a compact and robust laser system for atom interference on a sounding package [ J ] Applied Physics B,2016,122(8):217.) use 4 free space 780nm lasers, design miniaturized optics and use a stacked design, which can reduce the volume of the system to some extent, but require more devices, are more costly, consume more power, and have poor tunability, and require a lot of optical path alignment efforts in the previous optical path setup. In addition, a double laser light source system (Theron F, Bidel Y, Dieu E, et al. frequency-double selected fiber laser for a color interferometer using optical fibers [ J ] Optics Communications,2017,393: 152: 155.) developed by the French space navigation bureau is relatively mature, the 1560nm laser and the optical fiber frequency doubling technology are adopted for the system, the technical maturity is high, the space optical alignment is not needed, the difficulty of system construction is reduced, but the defects of large volume and high power consumption exist. Furthermore, the risk of system failure due to laser source breakdown is greater for multi-laser systems.

The single laser light source system scheme can save the cost and space of a plurality of lasers and has great attraction in the engineering of the atomic interference laser system. According to the optical frequency requirement for controlling atomic interference, a single laser light source system generally needs to obtain frequency-adjustable laser output by adopting a certain method, namely, the initial light frequency is changed according to the requirement of light with different frequencies, and then a sideband is generated through a phase modulator, so that laser output with various frequencies is generated. Typical single laser systems such as 1560nm fiber laser based single laser source system for on-board atomic interferometry developed by the french space agency (Theron F, Carraz O, Renon G, et al, narrow line width single laser source system for on-board atomic interferometry [ J ] Applied Physics B,2015,118(1):1-5.) use a phase modulator to generate sidebands and lock the +1 order sidebands onto the atomic transition spectrum line, change the output frequency of the laser by changing the modulation frequency Applied to the phase modulator, replace the slave laser and optical phase-locked loop in a dual laser system, subsequently generate sidebands by the phase modulator, and finally obtain the target light by a frequency doubling device. The system realizes all light in the atomic interference process only through a single laser, adopts an 1560nm optical fiber optical device, can improve system integration and reduce system volume, but provides high requirements for a frequency locking system and the bandwidth of a laser frequency modulation band because the frequency of the laser needs to be hopped in the system realization process, and has poor frequency locking effect. In addition, a compact single laser system (Fang Jie, Hu Jiangong, et al. reaction of a compact one-seed laser system for an atom interferometer-based gravimeters. [ J ]. Optics Express,2018 ]) has been proposed by wuhan article number, which uses a 780nm laser as a seed source, and also uses a phase modulator to generate sidebands and lock the +1 order sidebands on an atomic transition spectrum line, and then generates sidebands through the phase modulator to obtain target frequency light, but a 780nm band optical device is immature, high in cost and low in integration degree. In addition, the laser system scheme has sideband effect when generating Raman light, and has higher influence on atom interference precision.

Therefore, in order to solve the technical problems of the existing atomic interference laser system, an integrated single laser light source system which has low cost, low power consumption, mobility, small volume and Raman sideband effect elimination is urgently needed to be designed.

Disclosure of Invention

In order to solve the technical problems of the existing atomic interference laser system, the invention provides a cold atomic interferometer single laser light source system, which comprises:

the device comprises a reference light path module and an optical frequency shift module;

the reference optical path module comprises a laser and a frequency stabilization module, and is used for providing a frequency-stabilized and narrow-bandwidth laser source;

the optical frequency shift module comprises a first electro-optical modulator and a first narrow-bandwidth optical fiber filter, and the first electro-optical modulator and the first narrow-bandwidth optical fiber filter are connected through an optical fiber; the first electro-optical modulator is connected with the laser optical fiber;

the first electro-optical modulator receives initial light of a laser source, modulates the initial light through a modulation signal with a preset frequency, and generates a sideband with the preset frequency;

the first narrow-bandwidth optical fiber filter filters an optical signal output by the electro-optical modulator to obtain frequency shift light of a +1 order sideband; and the frequency shift light is used for modulating to obtain the measurement and control light of the cold atom interferometer.

Further, the reference light path module further includes a beam splitter, the beam splitter is disposed between the laser and the frequency stabilization module, one path of light output by the beam splitter is input to the frequency stabilization module, and the other path of light is input to the first electro-optic modulator.

Further, the beam splitter also outputs a path of blown light; the blown light is controlled by an optical control switch.

Furthermore, the optical frequency shift module is connected with the single-sideband modulation module through an optical fiber.

Further, the single-sideband modulation module comprises a second photoelectric modulator and a second narrow-bandwidth optical fiber filter; the second electro-optic modulator and the second narrow bandwidth fiber filter are connected by an optical fiber.

Further, the second narrow bandwidth fiber filter all includes optical circulator, grating, input, reflection output and transmission output, optical circulator links to each other with input, transmission output and reflection output respectively, the grating sets up between optical circulator and transmission output.

Further, the device also comprises an optical amplifier and an acousto-optic modulator; and the single-side band modulation module is sequentially connected with the optical amplifier and the acoustic-optical modulator through optical fibers.

The power control module is in electric signal connection with the acousto-optic modulator through the instantaneous power measurement and control module and is used for outputting light with stable total power.

Further, the device also comprises a power control module, wherein the power control module is used for modulating the voltage of the photoelectric modulator through the local vibration source and outputting light with stable power ratio.

Further, the laser is a 780nm laser or a 1560nm laser;

when the laser is 1560nm, the reference light and the measurement and control light output by the reference light path module and the optical frequency shift module need to be subjected to optical frequency doubling through the optical fiber amplifier and the frequency doubling crystal, and then the wavelength is converted into 780 nm.

The invention has the following beneficial effects:

(1) the cold atom interference laser system only uses one single-frequency laser source to finally realize the output of all laser frequencies of cold atom interference, and the laser device only needs to output fixed frequency for transition spectral line frequency stabilization without frequency hopping and frequency sweeping, thereby reducing the requirements on the frequency modulation bandwidth and performance of the laser device, expanding the selection range of the single-frequency laser source and enabling the laser source with small frequency modulation range, fast bandwidth response, small volume and low cost to be possible.

(2) At present, almost all phase modulation type light source systems use cooling light as base frequency light for phase modulation, frequency conversion is complex, high-frequency components of back-pumping light and Raman light are generated through frequency shift, the high-frequency components are used as fundamental frequencies, the phase modulation is used for generating the low-frequency components of the cooling light and the Raman light, a generation mechanism of the cooling light, the back-pumping light and a pair of Raman lights is innovated, the complexity of frequency control is reduced, and the stability of the system is improved.

(3) On the basis of laser frequency locking, the first electro-optical modulator EOM1 and the first narrow-bandwidth optical fiber filter NBOF1 are adopted to realize GHZ magnitude large frequency shift, the functions of a slave laser and a phase-locked loop in a multi-laser system are replaced, and the system size, the cost and the power consumption can be effectively reduced.

(4) The second electro-optical modulator EOM2 and the second narrow-bandwidth optical fiber filter NBOF2 are adopted to realize the generation of single-sideband Raman light, redundant sideband components generated by phase modulation are filtered through the second narrow-bandwidth optical fiber filter NBOF2, the Raman sideband effect caused by the Raman light generated by the phase modulation is effectively eliminated, and the atomic interference measurement precision is improved.

(5) A power stabilizing module is introduced, frequency stabilizing laser frequency, beat frequency detection of a pair of Raman lights and signal processing are ingeniously utilized to feed back and adjust modulation depth, high-efficiency, low-cost and fine stable control over Raman light power ratio is achieved, Stark effect is reduced, atomic level jitter caused by light intensity fluctuation, Raman light power ratio fluctuation and the like is particularly reduced, and influences on atomic interference measurement precision and long-term stability are reduced.

(6) The optical system for the atomic interferometer mainly adopts the optical fiber device at 1560nm communication waveband or 780nm communication waveband, has high integratable degree, low cost and small volume, only adopts a single laser source, generates the laser needed by the cold atomic interferometer by using an optical path multiplexing method, has the characteristics of high integration, low cost, low power consumption and mobility, and has important significance and practical value for the engineering realization of the laser system for high-precision atomic interferometry.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural diagram of a cold atom interferometer single laser light source system based on electro-optical modulation according to the present invention;

FIG. 2 is⁸⁷Schematic diagram of Rb atom interferometer measurement process;

FIG. 3 is⁸⁷Rb D2 line energy level and system laser frequency diagram;

FIG. 4 is a preferred embodiment of the present invention⁸⁷An integrated all-fiber single laser source optical system diagram of an Rb atom interferometer;

FIG. 5 is a schematic of the frequency relationships of the outputs and the bandwidth coverage of NBOF1 and NBOF 2;

FIG. 6 is a schematic diagram of a narrow bandwidth fiber filter architecture;

fig. 7 is a schematic diagram of the processes of cooling light, pump back light and raman light generation in optical multiplexing.

Detailed Description

Embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways, which are defined and covered by the claims.

As shown in fig. 1, a cold atom interferometer single laser light source system, the system comprising:

the device comprises a reference light path module and an optical frequency shift module;

the reference optical path module comprises a laser and a frequency stabilization module, and is used for providing a frequency-stabilized and narrow-bandwidth laser source;

the optical frequency shift module comprises a first electro-optical modulator and a first narrow-bandwidth optical fiber filter, and the first electro-optical modulator and the first narrow-bandwidth optical fiber filter are connected through an optical fiber; the first electro-optical modulator is connected with the laser optical fiber;

the first electro-optical modulator receives initial light of a laser source, modulates the initial light through a modulation signal with a preset frequency, and generates a sideband with the preset frequency;

the first narrow-bandwidth optical fiber filter filters an optical signal output by the electro-optical modulator to obtain frequency shift light of a +1 order sideband; and the frequency shift light is used for modulating to obtain the measurement and control light of the cold atom interferometer.

Because almost all the current phase modulation type light source systems use cooling light as base frequency light for phase modulation, and the frequency conversion is complex, the scheme provides that the measurement and control light for modulating to obtain cold atoms in an interferometer is generated by frequency shift, specifically high-frequency components of the pump-back light and the Raman light, and then the low-frequency components of the cooling light and the Raman light can be generated by phase modulation by taking the high-frequency components as the base frequency, so that the generation mechanisms of the cooling light, the pump-back light and the pair of Raman lights are innovated, the complexity of frequency control is reduced, and the stability of the system is improved.

In addition, on the basis of laser frequency locking, the first electro-optical modulator EOM1 and the first narrow-bandwidth optical fiber filter NBOF1 can realize GHZ-level large frequency shift, replace the functions of a slave laser and a phase-locked loop in a multi-laser system, and effectively reduce the volume, cost and power consumption of the system.

In one embodiment, the reference optical path module further includes a beam splitter, where the beam splitter is disposed between the laser and the frequency stabilization module, one path of light output by the beam splitter is input to the frequency stabilization module, and the other path of light is input to the first electro-optical modulator.

The beam splitter also outputs a path of blown light; the blown light is controlled by an optical control switch.

In one embodiment, the optical frequency shift module is connected with the single sideband modulation module through an optical fiber. Specifically, the single-sideband modulation module includes a second electro-optical modulator and a second narrow-bandwidth fiber filter; the second electro-optic modulator and the second narrow bandwidth fiber filter are connected by an optical fiber. The single-sideband modulation module also comprises an optical amplifier and an acousto-optic modulator; and the single-side band modulation module is sequentially connected with the optical amplifier and the acoustic-optical modulator through optical fibers.

As shown in fig. 6, each of the first and second narrow bandwidth fiber filters includes an optical circulator, a fiber bragg grating, an input port, a reflective output port, and a transmissive output port, the optical circulator is connected to the input port, the transmissive output port, and the reflective output port, respectively, and the grating is disposed between the optical circulator and the transmissive output port. The optical circulator is a multi-port non-reciprocal optical device, and incident light can only propagate in one direction in the optical circulator.

The second electro-optical modulator EOM2 and the second narrow-bandwidth optical fiber filter NBOF2 are adopted to realize the generation of single-sideband Raman light, redundant sideband components generated by phase modulation are filtered by the second narrow-bandwidth optical fiber filter NBOF2, the Raman sideband effect caused by the Raman light generated by the phase modulation is effectively eliminated, and the atomic interference measurement precision is improved.

In one embodiment, the system further comprises a power control module, wherein the power control module is electrically connected with the acousto-optic modulator through an instantaneous power measurement and control module and is used for outputting light with stable total power. The power control module can also modulate the voltage of the photoelectric modulator through the local vibration source and is used for outputting light with stable power ratio.

According to the invention, by introducing the power stabilizing module, the frequency stabilizing laser frequency, beat frequency detection of a pair of Raman lights and signal processing are skillfully utilized to feed back and adjust the modulation depth, so that high-efficiency, low-cost and fine stable control of the power ratio of the Raman lights can be realized, the Stark effect, especially atomic level jitter caused by light intensity fluctuation, Raman light power ratio fluctuation and the like, is reduced, and the influence of the Stark effect on the atomic interference measurement precision and long-term stability is reduced.

Specifically, the laser is a 780nm laser or a 1560nm laser. When the laser is 1560nm, the reference light and the measurement and control light output by the reference light path module and the optical frequency shift module need to be subjected to optical frequency doubling through the optical fiber amplifier and the frequency doubling crystal, and then the wavelength is converted into 780 nm.

The invention only uses a single-frequency laser source to finally realize the output of all laser frequencies of cold atom interference, and the laser only needs to output fixed frequency for transition spectral line frequency stabilization without frequency hopping and frequency sweeping, thereby reducing the requirements on the frequency modulation bandwidth and performance of the laser, expanding the selection range of the single-frequency laser source, and enabling the laser source with small frequency modulation range, fast bandwidth response, small volume and low cost to be possible.

⁸⁷The Rb atom interferometry process is shown in fig. 2, and includes four steps of atom cooling and trapping, initial state preparation, atom interference, and atom final state detection, and corresponds to laser outputs of a plurality of different frequencies and powers, such as cooling light, pumping back light, blowing light, raman light, and detection light, which are output by an integrated light source system. FIG. 3 is a drawing showing⁸⁷Rb D2 line energy level and system laser frequency diagram,⁸⁷the laser needed in the measurement process of the Rb atom interferometer comprises cooling light, back pumping light, blown light, Raman light and probe light. The cooling light and the pump-back light are two beams of laser light for atom cooling in the magneto-optical trap, and the frequency of the cooling light is set at a distance of |5²S_1/2,F＝2>→|5²S_3/2,F′＝3>Red detuning δ is 2 Γ to 6 Γ (where Γ is the natural line width and the frequency is about 6 MHz). Since the part | F ═ 2>The atom is transferred back to the "dark state" where | F ═ 1 > by the transition to the | F' 2 > energy level under the influence of cooling light, thus increasing |5²S_1/2,F＝1＞→|5²S_3/2F' 2 > resonates back to pump light, and the dark state atoms are re-pumped to | F ═ 2>And (4) forming a complete cooling cycle. Blow-off frequency is set at |5²S_1/2,F＝2>→|5²S_3/2,F′＝3>Here, the method is used to blow away all atoms remaining in F-2, leaving only | F-1, m_FWhen the atoms with the value of 0 > participate in subsequent interference, the blown light is a traveling wave in the use process, so that a subsequent optical path cannot be shared with the rest light, and separate output and switch control are needed. Raman light frequency was set at |5²S_1/2,F＝1>→|5²S_3/2,F′＝1>And |5²S_1/2,F＝2>→|5²S_3/2,F′＝1>At red detuning delta, the frequency difference is 6.834GHz, and the effect of interaction with atoms is realizedTwo-photon stimulated transition, the line width is required to be within 100kHz, and the phase difference is required to be locked at a constant value. The frequency of the probe light is the same as that of the blow-off light, and the probe light is used for detecting atoms as standing waves. As shown in fig. 2, in the atomic interference process, the laser output of the laser light source system with different frequencies and powers is realized through the time sequence control device along with the change of time.

In one particular embodiment of the present invention,⁸⁷an optical system diagram of an integrated all-fiber single laser source of an Rb atom interferometer is shown in fig. 4, and can be divided into two modules: the device comprises a reference light path module and a measurement and control light path module.

The reference light path module comprises a laser source 1560nm, a first erbium-doped fiber amplifier EDFA1, a first frequency doubling crystal PPLN1, an optical control switch OS and a frequency stabilization module, and is used for stabilizing the frequency of the laser, outputting blown light and providing a stable and narrow-bandwidth laser source for a subsequent measurement and control light path module. The 1560nm laser is subjected to power amplification through a first erbium-doped fiber amplifier EDFA1, and then is divided into two beams through a first beam splitter FS1, one beam is used for a subsequent measurement and control optical path module, and the other beam is input into a PPLN1 to carry out frequency doubling to obtain 780nm laser. 780nm output laser is divided into two beams by a second beam splitter FS2, and one beam of input light serving as a frequency stabilizing module locks 780nm light after frequency doubling of the laser at⁸⁷On the transition spectrum line of Rb 2 → F' 3, the other beam is directly output as the blow-off light after being connected to the optical control switch OS for controlling the blow-off light output.

The measurement and control optical path module has the characteristic of optical multiplexing, and can be used for outputting all laser (such as cooling light, back pump light, Raman light, probe light and the like) except for blown light (as shown in fig. 7). The measurement and control optical path module consists of a first electro-optical modulator EOM1, a second electro-optical modulator EOM2, a first narrow-bandwidth optical fiber filter NBOF1, a second narrow-bandwidth optical fiber filter NBOF2, a second erbium-doped optical fiber amplifier EDFA2, a third erbium-doped optical fiber amplifier EDFA3, an acousto-optic modulator AOM, a second frequency doubling crystal PPLN2, a power stabilizing module and an instantaneous power measurement and control module. As shown in FIG. 4, the laser source output frequency is f₀And/2, applying a frequency f to the EOM1 through a first local vibration source LO1₁High frequency signal producing sidebands, NBOF1 filtering out EOThe +1 order sideband of the M1, the two shift the output frequency of the laser source to the target position, then the power amplification is carried out by the EDFA2, the amplified signal is input into the EOM2, and the frequency f is applied by the second local oscillation source LO2₂The target laser is filtered out through NBOF2, signal power amplification is carried out through EDFA3, AOM is used for power control and switching of output laser, and finally frequency doubling is carried out through PPLN2 to output the target laser. The instantaneous power measurement and control module is used for measuring the output laser power and comparing the output laser power with the target power, the AOM is subjected to feedback control, the total power of output signals can be controlled, and the power stabilizing module is used for controlling the modulation voltage of the second local oscillator LO2 to achieve the stability of the power ratio due to the strict requirement on a pair of Raman lights in the Raman light output stage. The system can be used for providing the cold atom interferometer with the needed laser with different frequencies and different powers such as cooling light, back pumping light, blowing light, probe light, Raman light 1, Raman light 2 and the like.

In order to more vividly understand the working flow of the laser system in the atomic interference process, the laser output of the laser system at each stage is described according to the working timing sequence of the atomic interferometer in fig. 2.

In the atomic cooling phase, it is necessary to output cooling light and back-pump light at the same time. The generation process of cooling light and pumping light is shown in FIG. 4, 1560nm laser light branched from the reference light path is input into EOM1, and frequency f is applied to EOM1 by the first local oscillator LO1₁The modulation signal of 6.4GHz is input into a narrow bandwidth optical fiber filter NBOF1, the output bandwidth range of NBOF1 is shown in FIG. 5, the +1 order sideband generated by EOM1 is filtered out, the filtered signal is amplified by EDFA2 and then input into EOM2 as carrier light, and the frequency f is applied to EOM2 through a second local oscillator LO2₂The modulated light is input into NBOF2 at 6.4GHz modulation signal, NBOF2 has wide bandwidth range, the output bandwidth range is shown in FIG. 5, the carrier and-1 order sideband are filtered out, the carrier is amplified by EDFA3, the frequency of PPLN2 is doubled to obtain the pumping light as the carrier and the cooling light as-1 order sideband, and when the cooling light needs to be swept, the modulation frequency f of EOM2 is adjusted₂The frequency can be swept.

In the initial preparation stage, the Raman light is output first and then outputThe light was blown out. The generation of Raman light is shown in FIG. 4, in which the frequency of the voltage applied to the EOM1 is changed, and the EOM1 is applied with the frequency f by the first local oscillator LO1₁Generating a 5.484GHz sideband by the EOM1 after being modulated by an 5.484GHz modulation signal, obtaining a + 1-order sideband of the EOM1 after being processed by NBOF1, amplifying the sideband by an EDFA2, inputting the amplified sideband into the EOM2, and applying a frequency f to the EOM2 by a second local oscillator LO2₂Inputting a 6.834GHz modulation signal into NBOF2, wherein the NBOF2 has a large bandwidth range, the output bandwidth range is as shown in FIG. 5, filtering out the carrier and the-1 order sideband, obtaining a pair of Raman lights, then performing EDFA3 power amplification, performing PPLN2 frequency multiplication to obtain a target Raman light, and when the Raman light needs to be swept, adjusting the modulation frequency f of EOM2 by a second local oscillator LO2₂The frequency can be swept. And then controlling the AOM, closing the output of the Raman light, starting an optical control switch OS of the reference light path module, and outputting the blown light.

In the atomic interference stage, Raman light is required to be output according to the rule of pi/2-pi/2. And closing the optical control switch OS, adjusting the AOM, and opening the measurement and control light path module to output Raman light according to a rule.

In the final detection stage, the detection light is output according to the law of the detection light-the pumping back light-the detection light. At this time, the frequency f is applied to the EOM1 by the first local oscillator LO1₁The modulated signal of 6.4GHz is input into a narrow bandwidth optical fiber filter NBOF1, the +1 order sideband generated by EOM1 is filtered out and input into EOM2, and the frequency f is applied to EOM2 through a second local oscillator LO2₂And adjusting the modulation depth of the EOM2 modulation signal to enable the carrier optical power to be 0, outputting probe light at the moment, adjusting the modulation depth of the EOM2 again to enable the-1 order sideband optical power to be 0, outputting pump light at the moment, and finally adjusting the modulation depth of the EOM2 modulation signal again to enable the carrier optical power to be 0, outputting probe light, and realizing regular output of the probe light, the pump light and the probe light.

As shown in fig. 5, in the present invention, the frequency of the reference light is located between the frequency of the raman light 1 and the frequency of the raman light 2, and the frequency difference is 2.7GHz and 4.134GHz, respectively, so that the reference light can be used as a beat light to beat a pair of raman lights, and the power of two pairs of beat signals is monitored by the electronic module, so as to perform feedback control on the power ratio of the raman light 1 and the raman light 2, thereby skillfully realizing measurement and control of the raman light power ratio.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.