A narrow linewidth frequency-stabilized laser device and its working method

Abstract

The present invention belongs to the technical field of lasers, and discloses a narrow linewidth frequency-stabilized laser device and its working method. The device includes a laser module, a frequency-stabilized optical path module, and a frequency-stabilized control module. The laser module is used to output a first continuous laser, a second continuous laser, and a third continuous laser based on fundamental frequency light. The first continuous laser, the second continuous laser, and the third continuous laser are homologous lasers with different wavelengths. The frequency-stabilized optical path module is used to perform modulation transfer frequency stabilization on the second continuous laser by using the modulation transfer spectroscopy method, and output a frequency-stabilized detection signal. The frequency-stabilized control module is used to extract an amplitude signal from the frequency-stabilized detection signal to obtain a frequency discrimination signal, and generate a feedback signal according to the frequency discrimination signal. Among them, the feedback signal is used to trigger the laser module to perform tuning control on the fundamental frequency light, so that the frequency discrimination signal is always controlled at zero. The present invention can simultaneously output three homologous continuous lasers with different wavelengths, and all three continuous lasers have the characteristics of narrow linewidth and frequency stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of lasers, and particularly relates to a narrow linewidth frequency-stabilized laser device and its working method. Background Art

[0002] Due to its advantages such as good monochromaticity, high coherence, and good collimation, lasers are widely used in research in precision measurement, quantum metrology, and physical and precision spectroscopy measurement, etc. They are an important part of the light sources of various measurement systems, and the quality of their performance determines the upper limit of the accuracy of measurement results in most cases.

[0003] Currently, existing laser devices generally output continuous lasers with at most two wavelengths, such as a dual-wavelength frequency-doubled laser; due to the lack of a frequency-locking function, the output laser frequency is in a free-running state, and its laser frequency will drift over time; currently, there are also lasers that can output multi-wavelength continuous light, which use a frequency selection function to select a single wavelength for output, rather than outputting multiple laser wavelengths simultaneously, so essentially they cannot achieve the function of simultaneously outputting multiple continuous laser wavelengths and do not have a frequency-stabilized function; secondly, the relevant wavelengths of existing multi-wavelength laser devices have no correlation and are not from the same source. If frequency stabilization is performed on them later, the frequency stabilization system will be large in volume, high in cost, and poor in practicability. Summary of the Invention

[0004] Aiming at the technical problems existing in the prior art, the present invention provides a narrow linewidth frequency-stabilized laser device and its working method to solve the technical problems that existing multi-wavelength lasers cannot achieve the function of simultaneously outputting multiple continuous laser wavelengths and do not have a frequency-stabilized function.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a narrow linewidth frequency-stabilized laser device, including a laser module, a frequency-stabilized optical path module, and a frequency-stabilized control module;

[0007] The laser module is used to output a first continuous laser, a second continuous laser, and a third continuous laser based on fundamental frequency light; wherein, the first continuous laser, the second continuous laser, and the third continuous laser are laser lights from the same source and have different wavelengths;

[0008] The frequency-stabilized optical path module is used to perform modulation transfer frequency stabilization on the second continuous laser by using the modulation transfer spectroscopy method and output a frequency-stabilized detection signal;

[0009] The frequency stabilization control module is used to extract the amplitude signal from the frequency stabilization detection signal to obtain a frequency discrimination signal, and generate a feedback signal according to the frequency discrimination signal; wherein, the feedback signal is used to trigger the laser module to perform tuning control on the fundamental frequency light, so that the frequency discrimination signal is always controlled at zero value.

[0010] Further, the first continuous laser is 1064nm laser, the second continuous laser is 532nm laser, and the third continuous laser is 355nm laser.

[0011] Further, the laser module includes a laser generator, a first periodically poled crystal, a second periodically poled crystal, a first dichroic mirror, a second dichroic mirror, a beam splitter, and a first plane mirror; the laser generator is used to output fundamental frequency light; after the fundamental frequency light passes through the first periodically poled crystal, second harmonic light and part of the fundamental frequency light are formed; after the second harmonic light and the part of the fundamental frequency light pass through the second periodically poled crystal together, third harmonic light, the remaining second harmonic light, and the remaining fundamental frequency light are formed;

[0012] The third harmonic light, the remaining second harmonic light, and the remaining fundamental frequency light are incident on the first dichroic mirror together. After the third harmonic light passes through the first dichroic mirror, the third continuous laser is output; the remaining second harmonic light and the remaining fundamental frequency light are reflected by the first dichroic mirror and then incident on the second dichroic mirror together. After the remaining fundamental frequency light is reflected by the second dichroic mirror, the first continuous laser is output. The remaining second harmonic light passes through the second dichroic mirror and then is incident on the beam splitter; after the remaining second harmonic light passes through the beam splitter, a transmitted beam and a reflected beam are formed. The reflected beam is directly output to obtain the second continuous laser, and the transmitted beam is incident on the frequency stabilization optical path module after passing through the first plane mirror.

[0013] Further, the laser generator uses a 1064nm laser; wherein, the 1064nm laser has tuning and linear polarization functions.

[0014] Further, both the first periodically poled crystal and the second periodically poled crystal use periodically poled magnesium-doped lithium tantalate crystals.

[0015] Further, the light passing surface of the first dichroic mirror is coated with a 532nm high reflection film, a 1064nm high reflection film, and a 355nm high transmission film, and the light passing surface of the second dichroic mirror is coated with a 1064nm high reflection film and a 532nm high transmission film.

[0016] Further, the frequency stabilization optical path module includes a 1 / 2 wave plate, a first polarization beam splitter, an iodine cell, a second polarization beam splitter, a second plane mirror, an acousto-optic frequency shifter, a diaphragm, a third plane mirror, and a photodetector;

[0017] The transmitted light beam forms a probe light and a pump light after passing through a first plane mirror, a half-wave plate, and a first polarization beam splitter in sequence; the probe light directly enters the sensing area of the photodetector after passing through the iodine cell; the pump light forms a diffracted light after passing through a second plane mirror, an acousto-optic frequency shifter, and a diaphragm in sequence, and the diffracted light enters the iodine cell after passing through a third plane mirror and a second polarization beam splitter in sequence; wherein, the diffracted light and the probe light undergo nearly degenerate four-wave mixing in the iodine cell, so that under the action of iodine molecules in the iodine cell, the modulation sideband added to the pump light is transferred to the probe light, and a frequency-stabilized detection signal is generated and output in the photodetector.

[0018] Further, the frequency stabilization control module includes a lock-in amplifier and a dual-channel PID controller;

[0019] The input end of the lock-in amplifier is connected to the output end of the photodetector, and the output end of the lock-in amplifier is connected to the input end of the dual-channel PID controller; the first output end of the dual-channel PID controller is connected to the PZT tuning end of the laser generator, and the second output end of the dual-channel PID controller is connected to the laser crystal temperature tuning end of the laser generator;

[0020] The lock-in amplifier is used to perform phase adjustment and amplitude signal extraction on the frequency-stabilized detection signal to obtain a frequency discrimination signal; the dual-channel PID controller is used to receive and respond to the frequency discrimination signal to generate a feedback signal; wherein, the feedback signal includes a PZT tuning signal and a temperature tuning signal, the PZT tuning signal is input into the laser generator through the PZT tuning end of the laser generator, and the temperature tuning signal is input into the laser generator through the laser crystal temperature tuning end of the laser generator.

[0021] Further, the line shape expression of the frequency discrimination signal is specifically:

[0022]

[0023]

[0024] wherein, S' is the absorption spectrum signal after the action of the lock-in amplifier; C is the signal amplitude constant; Γ is the spectral line width; Ω is the modulation frequency of the modulator; J0(β) is the zero-order Bessel function; J1(β) is the first-order Bessel function; β is the modulation degree of the modulator; L n is the Lorentz line shape, that is, the expression of the absorption line shape, n is -1, -1 / 2, 1 / 2 or 1; L -1 is the absorption line shape function value when n is -1; L -1 / 2 is the absorption line shape function value when n is -1 / 2; L 1 / 2The absorption line shape function value when it is 1 / 2; the absorption line shape function value when L1 is 1; Δ is the laser frequency detuning amount, that is, the deviation value relative to the iodine cell resonance frequency.

[0025] The present invention also provides a working method of a narrow linewidth frequency-stabilized laser device, including:

[0026] Outputting a first continuous laser, a second continuous laser, and a third continuous laser based on the fundamental frequency light; wherein, the first continuous laser, the second continuous laser, and the third continuous laser are homologous lasers with different wavelengths;

[0027] Using the modulation transfer spectroscopy method to perform modulation transfer frequency stabilization on the second continuous laser, and outputting a frequency-stabilized detection signal;

[0028] Extracting an amplitude signal from the frequency-stabilized detection signal to obtain a frequency discrimination signal, and generating a feedback signal according to the frequency discrimination signal; wherein, the feedback signal is used to perform tuning control on the fundamental frequency light so that the frequency discrimination signal is always controlled at zero.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] The narrow linewidth frequency-stabilized laser device provided by the present invention can simultaneously output three continuous lasers that are homologous and have different wavelengths, and all three continuous lasers have the characteristics of narrow linewidth and frequency stability; specifically, the laser module simultaneously outputs three continuous lasers that are homologous and have different wavelengths based on the fundamental frequency light, and uses the frequency-stabilized detection signal output after performing modulation transfer frequency stabilization on the second continuous laser by the modulation transfer spectroscopy method to perform tuning control on the fundamental frequency light, so as to realize high-precision frequency stabilization control on the three continuous lasers simultaneously, so that the three continuous lasers have the same frequency stability, and can realize the narrowing of the laser linewidth while ensuring the stable locking of the laser wavelength; the device of the present invention can not only fully ensure the high accuracy of the laser light source, but also simplify the experimental or measurement device, realize the miniaturization of the laser device and the improvement of portability, and meet the research requirements of high-precision physical experiments and interference measurement technologies involving multiple frequency-stabilized light sources. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of the narrow linewidth frequency-stabilized laser device provided in Embodiment 1;

[0033] Figure 2The graph of the frequency detuning amount and amplitude of the narrow linewidth frequency-stabilized laser device in Embodiment 1.

[0034] Among them, 1 - laser generator, 2 - first periodically poled crystal, 3 - second periodically poled crystal, 4 - first dichroic mirror, 5 - second dichroic mirror, 6 - beam splitter, 7 - first plane mirror, 8 - 1 / 2 wave plate, 9 - first polarization beam splitter, 10 - iodine cell, 11 - second polarization beam splitter, 12 - second plane mirror, 13 - acousto-optic frequency shifter, 14 - aperture, 15 - third plane mirror, 16 - photodetector, 17 - modulation source, 18 - lock-in amplifier, 19 - dual-channel PID controller, 20 - high-voltage amplifier, 21 - attenuator. Detailed implementation manners

[0035] In order to make the technical problems, technical solutions and beneficial effects solved by this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application; obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0036] Embodiment 1

[0037] As shown in the attached Figure 1 drawing, Embodiment 1 of this application provides a narrow linewidth frequency-stabilized laser device, including a laser module, a frequency-stabilized optical path module and a frequency-stabilized control module; the laser module is used to output a first continuous laser, a second continuous laser and a third continuous laser based on the fundamental frequency light; among them, the first continuous laser, the second continuous laser and the third continuous laser are homologous lasers with different wavelengths; the frequency-stabilized optical path module is used to perform modulation transfer frequency stabilization on the second continuous laser by using the modulation transfer spectroscopy method and output a frequency-stabilized detection signal; the frequency-stabilized control module is used to extract an amplitude signal from the frequency-stabilized detection signal to obtain a frequency discrimination signal, and generate a feedback signal according to the frequency discrimination signal; among them, the feedback signal is used to trigger the laser module to perform tuning control on the fundamental frequency light so that the frequency discrimination signal is always controlled at zero.

[0038] In Embodiment 1 of this application, the laser module includes a laser generator 1, a first periodically poled crystal 2, a second periodically poled crystal 3, a first dichroic mirror (DM1) 4, a second dichroic mirror (DM2) 5, a beam splitter (BS1) 6 and a first plane mirror (M1) 7.

[0039] The laser generator 1 is used to output fundamental frequency light; specifically, the laser generator 1 is a 1064 nm laser, and the 1064 nm laser has tuning and linear polarization functions; preferably, the 1064 nm laser is a continuous laser with PZT fast tuning and stable slow tuning of the laser crystal; wherein, the fundamental frequency light is fundamental frequency light with a wavelength of 1064 nm.

[0040] After the fundamental frequency light passes through the first periodically poled crystal 2, second harmonic light and partial fundamental frequency light are formed; the second harmonic light and the partial fundamental frequency light together pass through the second periodically poled crystal 3 to form third harmonic light, remaining second harmonic light, and remaining third harmonic light; wherein, the second harmonic light is 532 nm second harmonic light, and the third harmonic light is 355 nm third harmonic light; both the first periodically poled crystal 2 and the second periodically poled crystal 3 are made of periodically poled magnesium-doped lithium tantalate crystal (PPMgSLT), and the periodically poled magnesium-doped lithium tantalate crystal (PPMgSLT) has a TEC temperature control function.

[0041] The third harmonic light, the remaining second harmonic light, and the remaining fundamental frequency light are incident on the first dichroic mirror (DM1) 4 together and then output to obtain the third continuous laser; wherein, the third continuous laser is 355 nm laser; the remaining second harmonic light and the remaining fundamental frequency light are reflected by the first dichroic mirror (DM1) 4 and then incident on the second dichroic mirror (DM2) 5 together, and the remaining fundamental frequency light is reflected by the second dichroic mirror (DM2) 5 and then output to obtain the first continuous laser; wherein, the first continuous laser is 1064 nm laser; the remaining second harmonic light passes through the second dichroic mirror (DM2) 5 and then is incident on the beam splitter (BS1) 6 to form a transmitted beam and a reflected beam, the reflected beam is directly output to obtain the second continuous laser, and the transmitted beam passes through the first plane mirror (M1) and then is incident on the frequency stabilization optical path module; wherein, the second continuous laser is 532 nm laser.

[0042] It should be noted that the light-transmitting surface of the first dichroic mirror (DM1) 4 is coated with a 532 nm high-reflection film, a 1064 nm high-reflection film, and a 355 nm high-transmission film, which is used for the third harmonic light to be directly output after transmission to obtain the third continuous laser, and is used for reflecting the remaining second harmonic light and the remaining fundamental frequency light, so that the remaining second harmonic light and the remaining fundamental frequency light are incident on the second dichroic mirror (5) together; the light-transmitting surface of the second dichroic mirror (DM2) 5 is coated with a 1064 nm high-reflection film and a 532 nm high-transmission film, which is used for reflecting the remaining fundamental frequency light and directly outputting the first continuous laser, and is used for the remaining second harmonic light to be incident on the beam splitter (BS1) 6 after transmission.

[0043] In this Embodiment 1, the frequency stabilization optical path module includes a half-wave plate (HWP) 8, a first polarization beam splitter (PBS1) 9, an iodine cell (I2 cell) 10, a second polarization beam splitter (PBS2) 11, a second plane mirror (M2) 12, an acousto-optic frequency shifter (AOM) 13, an aperture 14, a third plane mirror (M3) 15, and a photodetector (PD) 16.

[0044] The transmitted light beam forms a probe light and a pump light after passing through a first plane mirror (M1) 7, a half-wave plate (HWP) 8, and a first polarization beam splitter (PBS1) 9 in sequence; among them, the half-wave plate (HWP) 8 is a broadband half-wave plate; the probe light directly enters the sensing area of the photodetector (PD) 16 after passing through the iodine cell (I2 cell) 10; the pump light forms a diffracted light after passing through a second plane mirror (M2) 12, an acousto-optic frequency shifter (AOM) 13, and an aperture 14 in sequence; among them, the aperture 14 is used to select the first-order diffracted light of the acousto-optic frequency shifter (AOM) 13, that is, the diffracted light is the first-order diffracted light of the acousto-optic frequency shifter (AOM) 13; the diffracted light enters the iodine cell (I2 cell) 10 after passing through a third plane mirror (M3) 15 and a second polarization beam splitter 11 in sequence; among them, the diffracted light and the probe light undergo near-degenerate four-wave mixing in the iodine cell (I2 cell), so that under the action of iodine molecules in the iodine cell (I2 cell), the modulation sideband added to the pump light is transferred to the probe light, and a frequency stabilization detection signal is generated and output in the photodetector (PD) 16.

[0045] In this Embodiment 1, the frequency stabilization control module includes a modulation source (Modulation) 17, a lock-in amplifier (Lockin Amplifier) 18, a dual-channel PID controller (Dual-channel PID) 19, a high-voltage amplifier (High Voltage Amplifier) 20, and an attenuator (Attenuator) 21.

[0046] The output terminal of the photodetector (PD) 16 is connected to the first input terminal of the lock-in amplifier 18. The second input terminal of the lock-in amplifier 18 is connected to the first output terminal of the modulation source 17. The second output terminal of the modulation source 17 is connected to the input terminal of the acousto-optic frequency shifter (AOM) 13. The output terminal of the lock-in amplifier 18 is connected to the input terminal of the dual-channel PID controller 19. The first output terminal of the dual-channel PID controller 19 is connected to the input terminal of the high-voltage amplifier 20. The output terminal of the high-voltage amplifier 20 is connected to the PZT tuning terminal of the laser generator 1. The second output terminal of the dual-channel PID controller 19 is connected to the input terminal of the attenuator 21. The output terminal of the attenuator 21 is connected to the laser crystal temperature tuning terminal of the laser generator 1.

[0047] The modulation source 17 is used to generate and output a frequency modulation signal, which serves as the drive signal for the acousto-optic modulator (AOM) 13. The modulation source 17 is also used to output a synchronous modulation frequency signal, which serves as the reference input signal for the lock-in amplifier 18.

[0048] The lock-in amplifier 18 is used to receive and perform phase adjustment and amplitude signal extraction on the frequency-stabilized detection signal, and obtain and send a frequency discrimination signal to the dual-channel PID controller 19. The dual-channel PID controller 19 is used to respond to the frequency discrimination signal and generate a feedback signal. Among them, the feedback signal includes a PZT tuning signal and a temperature tuning signal. The PZT tuning signal is input into the laser generator 1 through the PZT tuning terminal of the laser generator 1, and the temperature tuning signal is input into the laser generator 1 through the laser crystal temperature tuning terminal of the laser generator 1.

[0049] It should be noted that the high-voltage amplifier 20 and the attenuator 21 are both added to match the tuning coefficient characteristics of the 1064 nm laser, and can be matched by means of multi-stage series connection or cancellation.

[0050] Working principle and working method:

[0051] The narrow-linewidth frequency-stabilized laser device described in Embodiment 1 has the following working principle: based on the fundamental frequency light, first continuous laser, second continuous laser, and third continuous laser are output; among them, the first continuous laser, the second continuous laser, and the third continuous laser are homologous lasers with different wavelengths; the modulation transfer spectroscopy method is used to perform modulation transfer frequency stabilization on the second continuous laser, and a frequency-stabilized detection signal is output; the amplitude signal of the frequency-stabilized detection signal is extracted to obtain a frequency discrimination signal, and a feedback signal is generated according to the frequency discrimination signal; among them, the feedback signal is used to perform tuning control on the fundamental frequency light so that the frequency discrimination signal is always controlled at zero.

[0052] Specifically, the working principle of the narrow-linewidth frequency-stabilized laser device is as follows:

[0053] The laser generator 1 generates and outputs fundamental frequency light, and the fundamental frequency light passes through the first periodically poled crystal 2 to generate second harmonic light and part of the fundamental frequency light; the second harmonic light and part of the fundamental frequency light jointly pass through the second periodically poled crystal 3 to generate third harmonic light, the remaining second harmonic light, and the remaining fundamental frequency light; subsequently, under the action of the first dichroic mirror 4, the third harmonic light is directly output as one of the output lights of the device to obtain the third continuous laser; while the remaining second harmonic light and the remaining fundamental frequency light are reflected onto the second dichroic mirror 5, and the remaining fundamental frequency light is selected by the second dichroic mirror 5 and output as another output light of the device to obtain the first continuous laser; then, under the action of the beam splitter 6, part of the remaining second harmonic light is reflected and output as the third output light of the device to obtain the second continuous laser; at this point, the device can output continuous lasers of three wavelengths, but each continuous laser is not frequency-stabilized and is in a free-running state.

[0054] After that, another part of the remaining frequency-doubled light is transmitted through the beam splitter 6 and enters the frequency stabilization optical path module through the first plane mirror 7, that is, the transmitted beam of the beam splitter 6 enters the frequency stabilization optical path module; in the frequency stabilization optical path module, under the action of the 1 / 2 wave plate and the first polarization beam splitter 9, the probe light and the pump light are distributed and adjusted according to a preset ratio; among them, the probe light passes through the iodine cell 10 and the second polarization beam splitter 11 and then directly enters the sensing area of the photodetector 16; while the pump light passes through the second plane mirror 12 and the acousto-optic frequency shifter 13 in sequence and then enters the aperture stop 14; the 1st order diffracted light of the acousto-optic frequency shifter 13 is selected by the aperture stop 14 to obtain the diffracted light; then, the extended light is reflected back to the second polarization beam splitter 11 by the third plane mirror 15 and then enters the iodine cell 10; in the iodine cell 10, the probe light and the pump light undergo nearly degenerate four-wave mixing, and under the action of iodine molecules in the iodine cell, the modulation sidebands added to the pump light are transferred to the probe light, and a frequency stabilization detection signal is generated and output in the photodetector 16.

[0055] Among them, the frequency stabilization detection signal is specifically:

[0056]

[0057]

[0058]

[0059] Among them, S(Ω) is the signal detected by the photodetector 16; C is the signal amplitude constant; Γ is the spectral line width; Ω is the modulation frequency of the modulator; J0(β) is the zero-order Bessel function; J1(β) is the first-order Bessel function; β is the modulation depth of the modulator; L n is the Lorentz line shape, that is, the absorption line shape function expression, n is -1, -1 / 2, 1 / 2 or 1; L -1 is the absorption line shape function value when n is -1; L -1 / 2 is the absorption line shape function value when n is -1 / 2; L 1 / 2 is the absorption line shape function value when it is 1 / 2; L1 is the absorption line shape function value when it is 1; D n is the dispersion line shape function expression, n takes values of -1, -1 / 2, 1 / 2; D -1 is the absorption line shape function value when it is -1; D -1 / 2 is the absorption line shape function value when it is -1 / 2; D 1 / 2 is the absorption line shape function value when it is 1 / 2; D1 is the absorption line shape function value when it is 1; Δ is the laser frequency detuning amount, that is, the deviation value relative to the iodine cell resonance frequency.

[0060] Next, after the frequency-stabilized detection signal enters the lock-in amplifier 18, by adjusting the phase and extracting the amplitude signal corresponding to the absorption line shape, a frequency discrimination signal is obtained; among them, the line shape expression of the frequency discrimination signal is:

[0061]

[0062] Among them, S' is the absorption spectrum signal after the lock-in amplification effect.

[0063] Appendix Figure 2 gives the curve graph of the frequency detuning amount and amplitude of the narrow linewidth frequency-stabilized laser device, that is, the curve graph of the frequency discrimination signal required for frequency stabilization; it can be seen from Appendix Figure 2 that when the laser frequency is near the resonance frequency of the iodine cell, according to the different deviation values of the laser frequency relative to the resonance frequency of the iodine cell, different amplitude characteristics of the absorption spectrum signal S' after the lock-in amplification effect can be obtained, and between the peak and valley of this signal, its signal characteristics are close to linear, which is very suitable for the locking of the laser frequency and PID feedback control.

[0064] Finally, the frequency discrimination signal is used as the input of the dual-channel PID controller, and a feedback signal is generated according to the frequency discrimination signal; the PZT tuning signal in the feedback signal acts on the PZT tuning port of the laser generator 1 through the high-voltage amplifier 20, and the temperature tuning signal in the feedback signal acts on the laser crystal temperature tuning end of the laser generator 1 through the attenuator 21; the laser generator 1 responds to the feedback signal to always control the frequency discrimination signal at zero value, so as to ensure that the laser wavelength is stably locked on the iodine molecule absorption spectrum line while being able to narrow the laser linewidth.

[0065] It should be noted that on the absorption spectrum line of the a 10 component of iodine molecule R(56)32-0, the relative standard uncertainty of the 532 nm frequency-doubled light wavelength value can reach 8.9×10 -12 , which can ensure that the 532 nm frequency-doubled light has a high stability; at the same time, since the first continuous laser, the second continuous laser and the third continuous laser are homologous lasers, the tuning control performed during the frequency stabilization process is a unified control of the fundamental frequency light, so the three wavelengths have the same frequency stability, that is, the laser device can output three standard continuous wavelengths, and all three wavelengths have the characteristics of narrow linewidth and frequency stability.

[0066] The narrow-linewidth frequency-stabilized laser device described in Embodiment 1 can simultaneously output three kinds of 1064nm lasers, 532nm lasers, and 355nm lasers of the same origin, and perform high-accuracy frequency stabilization on the three continuous lasers at the same time. The overall device has a small volume and a compact structure, and is very suitable for high-precision physical experiments and research on interference measurement technologies that require multiple frequency-stabilized light sources. It can not only fully ensure the high accuracy of the laser light source, but also simplify the experimental or measurement device, which is of great significance for the miniaturization of the device and the improvement of portability.

[0067] Embodiment 2

[0068] The structure and principle of the narrow-linewidth frequency-stabilized laser device provided in this Embodiment 2 are basically the same as those of the narrow-linewidth frequency-stabilized laser device described in Embodiment 1 above. The difference lies in that the broadband 1 / 2 waveplate is replaced by a multi-order 1 / 2 waveplate; among them, the multi-order 1 / 2 waveplate can satisfy the simultaneous transmission of the 532nm laser component; the rest of the components and principles in the device are basically the same as those of the laser device described in the embodiment, and will not be elaborated here.

[0069] Embodiment 3

[0070] The structure and principle of the narrow-linewidth frequency-stabilized laser device provided in this Embodiment 3 are basically the same as those of the narrow-linewidth frequency-stabilized laser device described in Embodiment 1 above. The difference lies in that the first plane mirror, the second plane mirror, and the third plane mirror are all replaced by right-angle prisms; the rest of the components and principles in the device are basically the same as those of the laser device described in the embodiment, and will not be elaborated here.

[0071] The narrow-linewidth frequency-stabilized laser device and its working method described in the present invention have the characteristics of a compact structure, and can simultaneously output three continuous laser wavelengths of the same origin, covering three typical wavelengths from ultraviolet to near-infrared, namely 1064nm laser, 532nm laser, and 355nm laser; at the same time, the device has PZT fast tuning and laser crystal temperature slow tuning functions. By performing modulation transfer frequency stabilization on the 532nm laser, based on the homologous relationship of the three wavelengths, the three wavelengths are simultaneously locked to a modulation transfer fine line with high accuracy and high stability, and then the purpose of performing high-accuracy frequency stabilization on the three continuous lasers at the same time is achieved.

[0072] The above embodiments are only one of the implementation manners that can realize the technical solution of the present invention. The scope of protection required by the present invention is not only limited by this embodiment, but also includes any changes, substitutions, and other implementation manners that are easily conceivable by those skilled in the art within the technical scope disclosed by the present invention.

Claims

1. A narrow linewidth frequency-stabilized laser device, characterized in that, It includes a laser module, a frequency stabilization optical path module and a frequency stabilization control module; The laser module is used to output a first continuous laser, a second continuous laser and a third continuous laser based on fundamental frequency light; wherein, the first continuous laser, the second continuous laser and the third continuous laser are homologous lasers with different wavelengths; The frequency stabilization optical path module is used to perform modulation transfer frequency stabilization on the second continuous laser by using the modulation transfer spectroscopy method and output a frequency stabilization detection signal; The frequency stabilization control module is used to extract an amplitude signal from the frequency stabilization detection signal to obtain a frequency discrimination signal and generate a feedback signal according to the frequency discrimination signal; wherein, the feedback signal is used to trigger the laser module to perform tuning control on the fundamental frequency light so that the frequency discrimination signal is always controlled at zero; The first continuous laser is a 1064nm laser, the second continuous laser is a 532nm laser, and the third continuous laser is a 355nm laser; The laser module includes a laser generator (1), a first periodically poled crystal (2), a second periodically poled crystal (3), a first dichroic mirror (4), a second dichroic mirror (5), a beam splitter (6) and a first plane mirror (7); the laser generator (1) is used to output fundamental frequency light; after the fundamental frequency light passes through the first periodically poled crystal (2), second harmonic light and part of the fundamental frequency light are formed; after the second harmonic light and the part of the fundamental frequency light pass through the second periodically poled crystal (3) together, third harmonic light, the remaining second harmonic light and the remaining fundamental frequency light are formed; The third harmonic light, the remaining second harmonic light and the remaining fundamental frequency light are incident on the first dichroic mirror (4) together. After the third harmonic light passes through the first dichroic mirror (4), the third continuous laser is output; the remaining second harmonic light and the remaining fundamental frequency light are reflected by the first dichroic mirror (4) and then incident on the second dichroic mirror (5) together. After the remaining fundamental frequency light is reflected by the second dichroic mirror (4), the first continuous laser is output. After the remaining second harmonic light passes through the second dichroic mirror (5), it is incident on the beam splitter (6); after the remaining second harmonic light passes through the beam splitter (6), a transmitted beam and a reflected beam are formed. The reflected beam is directly output to obtain the second continuous laser, and the transmitted beam is incident on the frequency stabilization optical path module after passing through the first plane mirror (7); The frequency stabilization optical path module includes a 1 / 2 wave plate (8), a first polarization beam splitter (9), an iodine cell (10), a second polarization beam splitter (11), a second plane mirror (12), an acousto-optic frequency shifter (13), a diaphragm (14), a third plane mirror (15) and a photodetector (16); The transmitted light beam forms a probe light and a pump light after passing through a first plane mirror (7), a half-wave plate (8), and a first polarization beam splitter (9) in sequence; the probe light directly enters the sensing area of the photodetector (16) after passing through the iodine cell (10); the pump light forms a diffracted light after passing through a second plane mirror (12), an acousto-optic frequency shifter (13), and a diaphragm (14) in sequence, and the diffracted light enters the iodine cell (10) after passing through a third plane mirror (15) and a second polarization beam splitter (11) in sequence; wherein, the diffracted light and the probe light undergo near-degenerate four-wave mixing in the iodine cell (10), so that under the action of iodine molecules in the iodine cell (10), the modulation sidebands added to the pump light are transferred to the probe light, and a frequency-stabilized detection signal is generated and output in the photodetector (16).

2. The narrow linewidth frequency-stabilized laser device according to claim 1, characterized in that The laser generator (1) uses a 1064 nm laser; wherein, the 1064 nm laser has tuning and linear polarization functions.

3. A narrow linewidth frequency-stabilized laser device according to claim 1, wherein Both the first periodically poled crystal (2) and the second periodically poled crystal (3) use periodically poled magnesium-doped lithium tantalate crystals.

4. A narrow linewidth frequency-stabilized laser device according to claim 1, characterized in that, The light-transmitting surface of the first dichroic mirror (4) is coated with a 532 nm high-reflection film, a 1064 nm high-reflection film, and a 355 nm high-transmission film, and the light-transmitting surface of the second dichroic mirror (5) is coated with a 1064 nm high-reflection film and a 532 nm high-transmission film.

5. A narrow linewidth frequency-stabilized laser device according to claim 1, characterized in that, The frequency stabilization control module includes a lock-in amplifier (18) and a dual-channel PID controller (19); The input end of the lock-in amplifier (18) is connected to the output end of the photodetector (16), and the output end of the lock-in amplifier (18) is connected to the input end of the dual-channel PID controller (19); the first output end of the dual-channel PID controller (19) is connected to the PZT tuning end of the laser generator (1), and the second output end of the dual-channel PID controller (19) is connected to the laser crystal temperature tuning end of the laser generator (1); The lock-in amplifier (18) is used to perform phase adjustment and amplitude signal extraction on the frequency-stabilized detection signal to obtain a frequency discrimination signal; the dual-channel PID controller (19) is used to receive and respond to the frequency discrimination signal to generate a feedback signal; wherein, the feedback signal includes a PZT tuning signal and a temperature tuning signal, the PZT tuning signal is input into the laser generator (1) through the PZT tuning end of the laser generator (1), and the temperature tuning signal is input into the laser generator (1) through the laser crystal temperature tuning end of the laser generator (1).

6. The narrow linewidth frequency-stabilized laser device according to claim 5, characterized in that, The line shape expression of the frequency discrimination signal is specifically:[[]] Among them, is the absorption spectrum signal after the action of the lock-in amplifier; is the signal amplitude constant; is the spectral linewidth; is the modulation frequency of the modulator; is the zero-order Bessel function; is the first-order Bessel function; is the modulation depth of the modulator; is the Lorentz line shape, that is, the expression of the absorption line shape, is -1, -1 / 2, 1 / 2 or 1; is is the function value of the absorption line shape when is is the function value of the absorption line shape when is the function value of the absorption line shape when is the function value of the absorption line shape when is the laser frequency detuning amount, that is, the deviation value relative to the iodine cell resonance frequency.

7. The working method of a narrow linewidth frequency-stabilized laser device according to any one of claims 1-6, characterized in that, Including:[[]] Output a first continuous laser, a second continuous laser, and a third continuous laser based on the fundamental frequency light; wherein, the first continuous laser, the second continuous laser, and the third continuous laser are homologous lasers with different wavelengths; Use the modulation transfer spectroscopy method to perform modulation transfer frequency stabilization on the second continuous laser, and output a frequency-stabilized detection signal; Extract the amplitude signal of the frequency-stabilized detection signal to obtain the frequency discrimination signal, and generate a feedback signal according to the frequency discrimination signal; wherein, the feedback signal is used to perform tuning control on the fundamental frequency light so that the frequency discrimination signal is always controlled at zero value.

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