Narrow-linewidth frequency-stabilized laser device and working method thereof

Abstract

The invention belongs to the technical field of lasers, and discloses a narrow-linewidth frequency-stabilized laser device and a working method thereof, and the device comprises a laser module, a frequency-stabilized light path module and a frequency-stabilized control module. The laser module is used for outputting first continuous laser, second continuous laser and third continuous laser based on the fundamental frequency light; the first continuous laser, the second continuous laser and the third continuous laser are homologous laser and have different wavelengths; the frequency stabilization light path module is used for carrying out modulation transfer frequency stabilization on the second continuous laser by utilizing a modulation transfer spectroscopy method and outputting a frequency stabilization detection signal; the frequency stabilization control module is used for performing amplitude signal extraction on the frequency stabilization 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 for triggering the laser module to perform tuning control on the fundamental frequency light, so that the frequency discrimination signal is always controlled at a zero value; three kinds of homologous continuous laser light with different wavelengths can be output at the same time, and the three kinds of continuous laser light have the advantages of being narrow in linewidth and stable in frequency.

Description

Technical Field

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

[0002] Lasers are widely used in research on precision measurement, quantum metrology, physics and precision spectral measurement due to their advantages such as good monochromaticity, high coherence and good collimation. They are an important component of the light source of each measurement system. The quality of their performance determines the upper limit of the accuracy of the measurement results in most cases.

[0003] At present, the existing laser devices generally output dual-wavelength continuous lasers at most, such as dual-wavelength frequency-doubling lasers; since they do not have a frequency-locking function, the output laser frequency is in a free-running state, and the laser frequency will drift over time; there are also lasers that can output multi-wavelength continuous light, which use a frequency selection function to select a single wavelength and then output it, rather than outputting the laser wavelengths simultaneously. Therefore, it is essentially impossible to achieve the function of simultaneously outputting multiple continuous laser wavelengths, and it does not have a frequency stabilization function; secondly, the related wavelengths of the existing multi-wavelength laser devices are not correlated and are not from the same source. If they are subsequently stabilized, the frequency stabilization system will be bulky, costly, and have poor practicality. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the present invention provides a narrow-linewidth frequency-stabilized laser device and a working method thereof to solve the technical problems that the existing multi-wavelength laser cannot realize the function of simultaneously outputting multiple continuous laser wavelengths and does not have the function of frequency stabilization.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a narrow linewidth frequency-stabilized laser device, comprising 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 the fundamental frequency light; wherein the first continuous laser, the second continuous laser and the third continuous laser are homologous lasers and have different wavelengths;

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

[0009] The frequency stabilization control module is used to extract the amplitude signal of the frequency stabilization detection signal to obtain a discrimination signal, and generate a feedback signal according to the 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 discrimination signal is always controlled at a zero value.

[0010] Furthermore, 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.

[0011] Further, the laser module includes a laser generator, a first periodic polarization crystal, a second periodic polarization 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; the fundamental frequency light forms doubled frequency light and part of the fundamental frequency light after passing through the first periodic polarization crystal; the doubled frequency light and part of the fundamental frequency light form tripled frequency light, remaining doubled frequency light and remaining fundamental frequency light after passing through the second periodic polarization crystal together;

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

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

[0014] Furthermore, the first periodically poled crystal and the second periodically poled crystal are both magnesium-doped lithium tantalate crystals with periodic poles.

[0015] Furthermore, the light-transmitting surface of the first dichroic mirror is coated with a 532nm high-reflection film, a 1064nm high-reflection film and a 355 high-transmittance film, and the light-transmitting surface of the second dichroic mirror is coated with a 1064nm high-reflection film and a 532nm high-transmittance film.

[0016] Furthermore, 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, an aperture, a third plane mirror and a photodetector;

[0017] The transmitted light beam passes through the first plane mirror, the 1 / 2 wave plate and the first polarization beam splitter in sequence to form a detection light and a pump light; the detection light passes through the iodine pool and is directly incident on the sensing area of ​​the photodetector; the pump light passes through the second plane mirror, the acousto-optic frequency shifter and the aperture in sequence to form a diffracted light, and the diffracted light passes through the third plane mirror and the second polarization beam splitter in sequence to enter the iodine pool; wherein the diffracted light and the detection light undergo nearly degenerate four-wave mixing in the iodine pool, so that under the action of iodine molecules in the iodine pool, the modulation sideband added to the pump light is transferred to the detection light, and a stable frequency detection signal is generated and output in the photodetector.

[0018] Furthermore, 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 phase-locked amplifier is used to perform phase adjustment and amplitude signal extraction on the stable frequency detection signal to obtain a discrimination signal; the dual-channel PID controller is used to receive and respond to the discrimination signal to generate a feedback signal; wherein the feedback signal includes a PZT tuning signal and a temperature tuning signal, wherein 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] Furthermore, the linear expression of the frequency discrimination signal is specifically:

[0022]

[0023]

[0024] Where S' is the absorption spectrum signal after the phase-locked amplifier; C is the signal amplitude constant; Γ is the spectrum 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 type, that is, the expression of the absorption line type, n is -1, -1 / 2, 1 / 2 or 1; L -1 is the absorption line function value when n is -1; L -1 / 2 is the absorption line function value when n is -1 / 2; L 1 / 2is the absorption line function value when L1 is 1 / 2; is the absorption line function value when L1 is 1; Δ is the laser frequency detuning, that is, the deviation value relative to the resonance frequency of the iodine cell.

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

[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 and have different wavelengths;

[0027] The second continuous laser is modulated and transferred to stabilize the frequency by using the modulation transfer spectroscopy method, and a stabilized frequency detection signal is output;

[0028] Amplitude signal extraction is performed on the frequency-stabilized detection signal to obtain a discrimination signal, and a feedback signal is generated according to the discrimination signal; wherein the feedback signal is used to tune and control the fundamental frequency light so that the discrimination signal is always controlled at a zero value.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The narrow linewidth frequency-stabilized laser device provided by the present invention can simultaneously output three continuous lasers of the same source and different wavelengths, and the three continuous lasers all have the characteristics of narrow linewidth and stable frequency. Specifically, the laser module simultaneously outputs three continuous lasers of the same source and different wavelengths based on the fundamental frequency light, and uses the frequency-stabilized detection signal output after the second continuous laser is modulated and transferred and frequency-stabilized based on the modulation transfer spectroscopy method to tune and control the fundamental frequency light, so as to achieve high-precision frequency-stabilized control of the three continuous lasers at the same time, so that the three continuous lasers have the same frequency stability, and can narrow the laser linewidth while ensuring the stable locking of the laser wavelength. The device of the present invention can fully guarantee the high accuracy of the laser light source, and can also simplify the experiment or measurement device, realize the miniaturization of the laser device and improve the portability, and meet the research requirements of high-precision physical experiments and interference measurement technology involving multiple frequency-stabilized light sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0033] Figure 21 is a curve diagram of the frequency detuning amount and amplitude of the narrow linewidth frequency-stabilized laser device in Example 1.

[0034] Among them, 1-laser generator, 2-first periodic polarization crystal, 3-second periodic polarization 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-acoustic-optic frequency shifter, 14-aperture, 15-third plane mirror, 16-photodetector, 17-modulation source, 18-phase-locked amplifier, 19-dual-channel PID controller, 20-high-voltage amplifier, 21-attenuator. DETAILED DESCRIPTION

[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 described clearly and completely in combination with the drawings in the embodiments of this application; obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] Example 1

[0037] As attached Figure 1 As shown, this embodiment 1 provides a narrow linewidth frequency-stabilized laser device, including a laser module, a frequency-stabilizing optical path module and a frequency-stabilizing 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-stabilizing optical path module is used to perform modulation transfer frequency stabilization on the second continuous laser using modulation transfer spectroscopy, and output a frequency-stabilized detection signal; the frequency-stabilizing control module is used to extract the amplitude signal of the frequency-stabilized detection signal to obtain a discrimination signal, and generate a feedback signal according to the 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 discrimination signal is always controlled at a zero value.

[0038] In this embodiment 1, the laser module includes a laser generator 1, a first periodic polarization crystal 2, a second periodic polarization 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 1064nm laser, and the 1064nm laser has tuning and linear polarization functions; preferably, the 1064nm laser is a continuous laser with PZT fast tuning and laser crystal stable slow tuning; wherein, the fundamental frequency light is fundamental frequency light with a wavelength of 1064nm.

[0040] After the fundamental frequency light passes through the first periodically polarized crystal 2, it forms doubled frequency light and part of the fundamental frequency light; after the doubled frequency light and part of the fundamental frequency light pass through the second periodically polarized crystal 3 together, they form tripled frequency light, remaining doubled frequency light and remaining tripled frequency light; wherein, the doubled frequency light is 532nm doubled frequency light, and the tripled frequency light is 355nm tripled frequency light; the first periodically polarized crystal 2 and the second periodically polarized crystal 3 both adopt magnesium-doped lithium tantalate crystal (PPMgSLT) with periodic polarization, and the magnesium-doped lithium tantalate crystal (PPMgSLT) with periodic polarization has TEC temperature control function.

[0041] The tripled frequency light, the remaining doubled frequency light and the remaining fundamental frequency light are incident on the first dichroic mirror (DM1) 4 together and then output to obtain a third continuous laser; wherein, the third continuous laser is a 355nm laser; the remaining doubled frequency 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 a first continuous laser; wherein, the first continuous laser is a 10664nm laser; the remaining doubled frequency light is transmitted through the second dichroic mirror (DM2) 5 and then incident on the beam splitter (BS1) 6 to form a transmitted light beam and a reflected light beam, and the reflected light beam is directly output to obtain a second continuous laser, and the transmitted light beam is incident on the frequency stabilization optical path module after passing through the first plane mirror (M1); wherein, the second continuous laser is a 532nm laser.

[0042] It should be noted that the light-transmitting surface of the first dichroic mirror (DM1) 4 is coated with a 532nm high-reflection film, a 1064nm high-reflection film and a 355 high-transmittance film, which is used to directly output the third continuous laser after the tripled frequency light is transmitted, and is used to reflect the remaining doubled frequency light and the remaining fundamental frequency light so that the remaining doubled frequency 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 1064nm high-reflection film and a 532nm high-transmittance film, which is used to directly output the remaining fundamental frequency light after reflection to obtain the first continuous laser, and is used to allow the remaining doubled frequency 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 1 / 2 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 (Aperture) 14, a third plane mirror (M3) 15 and a photodetector (PD) 16.

[0044] The transmitted light beam is sequentially passed through a first plane mirror (M1) 7, a half wave plate (HWP) 8 and a first polarization beam splitter (PBS1) 9 to form a detection light and a pump light; wherein the half wave plate (HWP) 8 is a broadband half wave plate; the detection light is directly incident on a sensing area of ​​the photodetector (PD) 16 after passing through the iodine cell (I2 cell) 10; the pump light is sequentially passed through a second plane mirror (M2) 12, an acousto-optic frequency shifter (AOM) 13 and an aperture (Aperture) 14 to form a diffracted light; wherein the aperture (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 is sequentially passed through a third plane mirror (M3) 15 and a second polarization beam splitter 11 to enter the iodine cell (I2 cell) 16; cell) 10; wherein, the diffracted light and the detection light undergo nearly degenerate four-wave mixing in the iodine cell (I2 cell) 10, so that under the action of iodine molecules in the iodine cell (I2 cell) 10, the modulation sideband added to the pump light is transferred to the detection light, and a stable frequency detection signal is generated and output in the photodetector (PD) 16.

[0045] In the first embodiment, 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 end of the photodetector (PD) 16 is connected to the first input end of the phase-locked amplifier (Lock in Amplifier) ​​18, the second input end of the phase-locked amplifier (Lock in Amplifier) ​​18 is connected to the first output end of the modulation source (Modulation) 17, and the second output end of the modulation source (Modulation) 17 is connected to the input end of the acousto-optic frequency shifter (AOM) 13; the output end of the phase-locked amplifier (Lock in Amplifier) ​​18 is connected to the input end of the dual-channel PID controller (Dual-channel PID) 19, the first output end of the dual-channel PID controller (Dual-channel PID) 19 is connected to the input end of the high-voltage amplifier (High Voltage Amplifier) ​​20, and the output end of the high-voltage amplifier (High Voltage Amplifier) ​​20 is connected to the PZT tuning end of the laser generator 1; the dual-channel PID controller (Dual-channel The second output end of the PID 19 is connected to the input end of the attenuator 21 , and the output end of the attenuator 21 is connected to the laser crystal temperature tuning end of the laser generator 1 .

[0047] The modulation source (Modulation) 17 is used to generate and output a frequency modulation signal, and serves as a driving signal for the acousto-optic modulator (AOM) 13; the modulation source (Modulation) 17 is also used to output a synchronized modulation frequency signal, and serves as a reference input signal for the lock-in amplifier (Lock in Amplifier) ​​18.

[0048] The phase-locked amplifier (Lock in Amplifier) ​​18 is used to receive and perform phase adjustment and amplitude signal extraction on the stable frequency detection signal, obtain and send a discrimination signal to the dual-channel PID controller (Dual-channel PID) 19; the dual-channel PID controller (Dual-channel PID) 19 is used to respond to the discrimination signal and 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.

[0049] It should be noted that the high-voltage amplifier 20 and the attenuator 21 are added to match the tuning coefficient characteristics of the 1064nm laser, and can be matched by connecting multiple stages in series or canceling them.

[0050] Working principle and working method:

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

[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 generates frequency-doubled light and part of the fundamental frequency light through the first periodic polarization crystal 2; the frequency-doubled light and part of the fundamental frequency light pass through the second periodic polarization crystal 3 together to generate tripled frequency light, remaining frequency-doubled light and remaining fundamental frequency light; then, under the action of the first dichroic mirror 4, the tripled frequency light is directly output as one of the output lights of the device to obtain the third continuous laser; while the remaining frequency-doubled light and the remaining fundamental frequency light are reflected on the second dichroic mirror 5, and the remaining fundamental frequency light is screened out by the second dichroic mirror 5 as another output light of the device to obtain the first continuous laser; then, the remaining frequency-doubled light reflects a part of the remaining frequency-doubled light under the action of the beam splitter 6 as the third output light of the device to obtain the second continuous laser; so far, the device can output continuous lasers with three wavelengths, but each continuous laser is not frequency stabilized and is in a free-running state.

[0054] Afterwards, another part of the remaining doubled frequency 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 light beam of the beam splitter 6 enters the frequency stabilization optical path module; in the frequency stabilization optical path module, the transmitted light beam is passed through the 1 / 2 wave plate and the first polarization beam splitter 9 to achieve the distribution and adjustment of the detection light and the pump light according to the preset ratio; wherein, after the detection light passes through the iodine cell 10 and the second polarization beam splitter 11, it is directly incident on the sensing area of ​​the photodetector 16; and the pump light passes through the iodine cell 10 and the second polarization beam splitter 11 in sequence. The second plane mirror 12 and the acousto-optic frequency shifter 13 are then incident on the aperture 14; the first-order diffraction light of the acousto-optic frequency shifter 13 is selected by the aperture 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 pool 10; in the iodine pool 10, the detection light and the pump light undergo nearly degenerate four-wave mixing, and under the action of the iodine molecules in the iodine pool, the modulation sideband added to the pump light is transferred to the detection light, and a stable frequency detection signal is generated and output in the photodetector 16.

[0055] The frequency stabilization detection signal is specifically:

[0056]

[0057]

[0058]

[0059] Wherein, 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 degree of the modulator; L n is the Lorentz line type, that is, the absorption line type function expression, n is -1, -1 / 2, 1 / 2 or 1; L -1 is the absorption line function value when n is -1; L -1 / 2 is the absorption line function value when n is -1 / 2; L 1 / 2 =1 / 2; =1; =1; =D n is the dispersion linear function expression, n takes values ​​of -1, -1 / 2, 1 / 2; D -1 The absorption line function value when D is -1; -1 / 2 The absorption line function value when D is -1 / 2; 1 / 2 is the absorption line function value when D1 is 1 / 2; is the absorption line function value when D1 is 1; Δ is the laser frequency detuning, that is, the deviation value relative to the resonance frequency of the iodine cell.

[0060] Next, after the frequency-stabilized detection signal enters the phase-locked amplifier 18, the phase is adjusted and the amplitude signal of the corresponding absorption line is extracted to obtain the frequency discrimination signal; wherein, the linear expression of the frequency discrimination signal is:

[0061]

[0062] Among them, S' is the absorption spectrum signal after phase-locked amplification.

[0063] Attached Figure 2 The frequency detuning amount and amplitude curve of the narrow linewidth frequency stabilization laser device is given in the figure, that is, the curve of the frequency discrimination signal required for frequency stabilization; Figure 2 It can be seen that when the laser frequency is near the resonance frequency of the iodine pool, different amplitude characteristics of the absorption spectrum signal S' after phase-locked amplification can be obtained according to the different deviation values ​​of the laser frequency relative to the resonance frequency of the iodine pool, and the signal characteristics are close to linear between the peaks and troughs of the signal, which is very suitable for laser frequency locking and PID feedback control.

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

[0065] It should be noted that in the iodine molecule R(56)32-0 10 The relative standard uncertainty of the wavelength value of 532nm double frequency light can reach 8.9×10 -12 , which can ensure that the 532nm 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 in 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 the three wavelengths all have the characteristics of narrow linewidth and frequency stability.

[0066] The narrow-linewidth frequency-stabilized laser device described in Example 1 can simultaneously output three homologous 1064nm lasers, 532nm lasers and 355nm lasers, and simultaneously perform high-precision frequency stabilization on the three continuous lasers. The overall device is small in size and compact in structure, and is very suitable for high-precision physical experiments and interferometric measurement technology research that require the participation of multiple frequency-stabilized light sources. It can fully ensure the high accuracy of the laser light source and simplify the experimental or measuring device, which is of great significance to the miniaturization of the device and the improvement of portability.

[0067] Example 2

[0068] The narrow-linewidth frequency-stabilized laser device provided in this embodiment 2 is basically the same in structure and principle as the narrow-linewidth frequency-stabilized laser device described in the above embodiment 1, except that: the broadband 1 / 2 wave plate is replaced by a multi-order 1 / 2 wave plate; wherein the multi-order 1 / 2 wave plate can meet the simultaneous transmission of 532nm laser components; the remaining components and principles in the device are basically the same as the laser device described in the embodiment, and will not be repeated here.

[0069] Example 3

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

[0071] The narrow-linewidth frequency-stabilized laser device and the working method thereof described in the present invention have the characteristics of compact structure, and can simultaneously output three homologous continuous laser wavelengths, covering three typical wavelengths from ultraviolet to near infrared, namely 1064nm laser, 532nm laser and 355nm laser; at the same time, the device has the functions of PZT fast tuning and laser crystal temperature slow tuning, and by modulating and transferring the 532nm laser to stabilize the frequency, based on the homologous relationship of the three wavelengths, the three wavelengths can be simultaneously locked to the high-accuracy and high-stability modulation transfer fine spectrum line, thereby achieving the purpose of simultaneously stabilizing the three continuous lasers with high accuracy.

[0072] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field 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 the fundamental frequency light; wherein the first continuous laser, the second continuous laser and the third continuous laser are homologous lasers and have different wavelengths; The frequency stabilization optical path module is used to perform modulation transfer frequency stabilization on the second continuous laser by using modulation transfer spectroscopy, and output a frequency stabilization detection signal; The frequency stabilization control module is used to extract the amplitude signal of the frequency stabilization detection signal to obtain a discrimination signal, and generate a feedback signal according to the 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 discrimination signal is always controlled at a zero value.

2. A narrow linewidth frequency-stabilized laser device according to claim 1, characterized in that: The first continuous laser is a 1064 nm laser, the second continuous laser is a 532 nm laser, and the third continuous laser is a 355 nm laser.

3. A narrow linewidth frequency-stabilized laser device according to claim 2, characterized in that: The laser module comprises a laser generator (1), a first periodic polarization crystal (2), a second periodic polarization 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 periodic polarization crystal (2), it forms doubled frequency light and part of the fundamental frequency light; after the doubled frequency light and part of the fundamental frequency light pass through the second periodic polarization crystal (3), they form tripled frequency light, remaining doubled frequency light and remaining fundamental frequency light; The tripled frequency light, the remaining doubled frequency light and the remaining fundamental frequency light are incident on the first dichroic mirror (4) together, and the tripled frequency light is transmitted through the first dichroic mirror (4) and then output to obtain the third continuous laser; the remaining doubled frequency 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, and the remaining fundamental frequency light is reflected by the second dichroic mirror (4) and then output to obtain the first continuous laser, and the remaining doubled frequency light is transmitted through the second dichroic mirror (5) and then incident on the beam splitter (6); the remaining doubled frequency light forms a transmitted light beam and a reflected light beam after passing through the beam splitter (6), and the reflected light beam is directly output to obtain the second continuous laser, and the transmitted light beam is incident on the frequency stabilization optical path module after passing through the first plane mirror (7).

4. A narrow linewidth frequency-stabilized laser device according to claim 3, characterized in that: The laser generator (1) adopts a 1064nm laser; wherein the 1064nm laser has tuning and linear polarization functions.

5. A narrow linewidth frequency-stabilized laser device according to claim 3, characterized in that: The first periodically poled crystal (2) and the second periodically poled crystal (3) are both magnesium-doped lithium tantalate crystals with periodic poles.

6. A narrow linewidth frequency-stabilized laser device according to claim 3, characterized in that: The light-transmitting surface of the first dichroic mirror (4) is coated with a 532nm high-reflection film, a 1064nm high-reflection film and a 355 high-transmittance film, and the light-transmitting surface of the second dichroic mirror (5) is coated with a 1064nm high-reflection film and a 532nm high-transmittance film.

7. A narrow linewidth frequency-stabilized laser device according to claim 3, characterized in that: The frequency stabilization optical path module comprises a half 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), an aperture (14), a third plane mirror (15) and a photoelectric detector (16); The transmitted light beam passes through a first plane mirror (7), a half wave plate (8) and a first polarization beam splitter (9) in sequence to form a detection light and a pump light; the detection light passes through the iodine pool (10) and is directly incident on a sensing area of ​​the photodetector (16); the pump light passes through a second plane mirror (12), an acousto-optic frequency shifter (13) and an aperture (14) in sequence to form a diffracted light, and the diffracted light passes through a third plane mirror (15) and a second polarization beam splitter (11) in sequence to enter the iodine pool (10); wherein the diffracted light and the detection light undergo near-degenerate four-wave mixing in the iodine pool (10), so that under the action of iodine molecules in the iodine pool (10), a modulation sideband applied to the pump light is transferred to the detection light, and a frequency-stabilized detection signal is generated and output in the photodetector (16).

8. A narrow linewidth frequency-stabilized laser device according to claim 7, characterized in that: The frequency stabilization control module comprises a phase-locked 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 phase-locked amplifier (18) is used to perform phase adjustment and amplitude signal extraction on the stable frequency detection signal to obtain a discrimination signal; the dual-channel PID controller (19) is used to receive and respond to the discrimination signal to generate a feedback signal; wherein the feedback signal includes a PZT tuning signal and a temperature tuning signal, wherein 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).

9. A narrow linewidth frequency-stabilized laser device according to claim 8, characterized in that: The linear expression of the frequency discrimination signal is specifically: Where S' is the absorption spectrum signal after the phase-locked amplifier; C is the signal amplitude constant; Γ is the spectrum 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 type, that is, the expression of the absorption line type, n is -1, -1 / 2, 1 / 2 or 1; L -1 is the absorption line function value when n is -1; L -1 / 2 is the absorption line function value when n is -1 / 2; L 1 / 2 is the absorption line function value when L1 is 1 / 2; is the absorption line function value when L1 is 1; Δ is the laser frequency detuning, that is, the deviation value relative to the resonance frequency of the iodine cell.

10. A method for operating a narrow linewidth frequency-stabilized laser device according to any one of claims 1 to 9, characterized in that: include: 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 and have different wavelengths; The second continuous laser is modulated and transferred to stabilize the frequency by using the modulation transfer spectroscopy method, and a stabilized frequency detection signal is output; Amplitude signal extraction is performed on the frequency-stabilized detection signal to obtain a discrimination signal, and a feedback signal is generated according to the discrimination signal; wherein the feedback signal is used to tune and control the fundamental frequency light so that the discrimination signal is always controlled at a zero value.

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