Device and method for stabilizing any detuning frequency of laser

Abstract

The invention provides a frequency stabilization device and method for any detuning frequency of a laser. The frequency stabilization device comprises a pumping laser atomic resonance point frequency stabilization structure, a cavity length locking structure of an optical resonant cavity and a frequency stabilization structure for detecting any detuning frequency of the laser. The frequency of the pumping laser is stabilized at an atomic resonance point through a saturated absorption frequency stabilization method, and then the cavity length of an optical resonant cavity is locked by taking the frequency-stabilized pumping light as a reference. Two modulation signals with different frequencies are superposed by adopting Bias Tee, biphase modulation is applied to detection laser through an electro-optic phase modulator, a stable error signal is demodulated while a modulation sideband is generated, then a first-order sideband is locked on a longitudinal mode, close to an optimal detuning point, of an optical resonant cavity, and a second-order sideband is locked on a longitudinal mode, close to the optimal detuning point, of the optical resonant cavity. Continuous frequency tuning in the laser frequency stabilization process is detected by adjusting the first-order sideband frequency. According to the invention, the size and the cost are reduced.

Description

Technical Field

[0001] The present invention relates to the field of laser frequency stabilization control in quantum precision measurement technology, in particular to the technical field of detuned frequency stabilization of non-atomic resonance points of lasers, and specifically to a laser arbitrary detuned frequency stabilization device and method. Background Art

[0002] In the field of atomic spin inertial measurement, the frequency stability of the detection laser will affect the atomic polarization performance and the optical rotation angle detection performance, thus directly affecting the accuracy and stability of the atomic spin inertial measurement system. In order to achieve stable atomic polarization performance, the operating frequency of the pump laser needs to be stable at the atomic resonance point, and in order to suppress the pumping effect introduced by the detection laser on the atom, the operating frequency of the detection laser needs to deviate from the alkali metal atomic absorption line. Studies have shown that there is an optimal frequency point that can maximize the suppression of the effect of the detection laser on the atomic spin polarization performance. In addition, the optimal frequency detuning point of the detection laser will vary with different conditions of the alkali metal gas chamber in the atomic spin inertial measurement system, such as gas chamber temperature, atomic density and initial pumping light power. Although the atomic resonance frequency is stable, it cannot support the detuning frequency stabilization of the detection laser because its frequency is fixed. The longitudinal mode of the optical resonant cavity can be used as a reference for laser frequency stabilization, and its longitudinal mode is widely distributed, so the laser frequency is locked to a certain longitudinal mode of the optical resonant cavity to achieve detuning frequency stabilization, such as PDH (Pound-Drever-Hall) frequency stabilization technology. However, the longitudinal mode distribution of the optical resonant cavity is not continuous, and there is a large frequency interval between adjacent longitudinal modes, which is called the free spectral range. This will limit the frequency tuning of the laser locked in the optical resonant cavity, which will not meet the requirements of the atomic spin inertial measurement system to detect the laser reaching the optimal frequency detuning point. In addition, the cavity length of the optical resonant cavity is sensitive to environmental disturbances such as temperature fluctuations and mechanical vibrations, which leads to poor stability of the laser frequency locked in the cavity. The use of an ultra-stable cavity with high stability placed in a vacuum chamber can suppress the cavity length drift of the resonant cavity to a certain extent, but this solution is very large and costly, making it difficult to apply. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a device and method for stabilizing the frequency of arbitrary detuning laser. The device mainly includes a pump laser atomic resonance point frequency stabilization optical path, an optical resonant cavity locking optical path and a detection laser arbitrary detuning frequency stabilization optical path. The pump laser is stabilized at the atomic resonance point by a saturated absorption frequency stabilization method, and then the cavity length of the optical resonant cavity is locked with the pump light after frequency stabilization as a reference. A Bias Tee (radio frequency bias device) is used to superimpose two modulation signals of different frequencies, and a dual-phase modulation is applied to the detection laser by an electro-optical phase modulator. A stable error signal is demodulated while generating a modulation sideband, and then the first-order sideband is locked on the longitudinal mode of the optical resonant cavity close to the optimal detuning point. The frequency is continuously tuned during the frequency stabilization of the detection laser by adjusting the first-order sideband frequency, so that the detection laser frequency is accurately tuned to the optimal frequency detuning point while ensuring frequency stability. The present invention enables the detection laser to obtain frequency stability comparable to the atomic resonance frequency at any frequency point within its frequency tuning bandwidth, and a small-volume commercial optical resonant cavity can be used without considering its stability, so that both the volume and cost are reduced.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A laser arbitrary detuned frequency stabilization device comprises a pumping laser atomic resonance point frequency stabilization optical path, an optical resonant cavity locking optical path and a detection laser arbitrary detuned frequency stabilization optical path; the pumping light atomic resonance point frequency stabilization optical path is used to lock the pumping light frequency to the atomic resonance point, the optical resonant cavity locking optical path uses the stabilized pumping light as the frequency standard and locks the cavity length of the optical resonant cavity to the pumping light; the detection laser arbitrary detuned frequency stabilization optical path locks the detection laser to the optical resonant cavity.

[0006] Furthermore, the pumping laser atomic resonance point frequency stabilization optical path includes a pumping laser, a first optical isolator, a first half-wave plate, a first polarization beam splitter, a 50:50 reflective mirror, an atomic gas chamber, a first reflector, a first photodetector, a first signal generator, a first frequency detector, a first low-pass filter, a first PI controller, and a power divider; after the pumping laser with a central wavelength of 770 nm passes through the first optical isolator, it is divided into two parts through the first half-wave plate and the first polarization beam splitter: the reflected part enters the 50:50 reflective mirror and then is reflected into the potassium atomic gas chamber to generate pump light, the pump light is reflected back to the potassium atomic gas chamber by the first reflector as detection light, the pump light and the detection light intersect to generate a saturated absorption spectrum, and the detection light carrying spectral information passes through the 50:50 reflective mirror and is detected by the first photodetector; the first signal generator generates a sweep frequency signal and a frequency of The modulated signal is then input into the power divider, one end of the power divider is connected to the pump laser, and the other end is connected to the phase shifter; the first signal generator simultaneously generates a frequency of The demodulated signal is input to the first frequency detector, the signal detected by the first photodetector is output to the first frequency detector, mixed with the demodulated signal and demodulated to obtain an error signal, which is then transmitted to the first PI controller after passing through the first low-pass filter and generates a feedback control signal, and the control signal is finally transmitted to the pump laser frequency tuning port to achieve laser frequency locking.

[0007] Furthermore, the optical resonant cavity locking optical path includes a second reflector, a second half-wave plate, a second polarization beam splitter prism, a first quarter-wave plate, a dichroic mirror, a convex lens, an optical resonant cavity, a piezoelectric ceramic, a second photodetector, a phase shifter, a second frequency detector, a second low-pass filter, and a second PI controller; the portion transmitted by the first polarization beam splitter prism is reflected by the second reflector, and then sequentially passes through the second half-wave plate, the second polarization beam splitter prism, the first quarter-wave plate, the dichroic mirror, and the convex lens before being coupled into the optical resonant cavity, containing the resonant cavity phase information The reflected light will return along the original optical path, pass through the convex lens and the dichroic mirror in turn, and then be reflected by the second polarization splitter prism into the second photodetector; the signal at the other end of the power divider is regarded as a demodulated signal after passing through the phase shifter, and then sent to the second frequency detector and phase detector, and the signal detected by the second photodetector is output to the second frequency detector and mixed with the demodulated signal to demodulate the error signal, which is transmitted to the second PI controller after passing through the second low-pass filter and generates a feedback control signal, and then transmitted to the port of the piezoelectric ceramic 32 of the optical resonant cavity to achieve cavity length locking of the optical resonant cavity.

[0008] Furthermore, the detection laser arbitrary detuned frequency stabilization optical path includes a detection laser, a second optical isolator, a third half-wave plate, an electro-optical phase modulator, a third polarization beam splitter prism, a second quarter-wave plate, a third photodetector, a third frequency and phase detector, a second signal generator, a radio frequency source, a radio frequency amplifier, a Bias Tee, an EOM driver, a third low-pass filter, a third PI controller, and an adder; the laser light from the detection laser with a central wavelength of 795 nm passes through the second optical isolator, and then passes through the third half-wave plate, the electro-optical phase modulator, the third polarization beam splitter prism, and the second quarter-wave plate in sequence, and is reflected by the dichroic mirror, and then is coupled into the optical resonant cavity through a convex lens, and the reflected light containing the phase information of the resonant cavity will return along the original optical path, pass through the convex lens, be reflected by the dichroic mirror, and enter the third polarization beam splitter prism, and be reflected by it into the third photodetector; the radio frequency source generates a frequency of The high frequency modulation signal is output to the RF port of the Bias Tee, and the second signal generator generates a frequency of A relatively low-frequency modulation signal is amplified by the RF amplifier and then output to the DC port of the BiasTee. The RF&DC port of the Bias Tee is connected to the EOM driver, and then the electro-optical phase modulator is driven to apply dual-phase modulation to the detection laser; the detection laser frequency is tuned to the optimal detuning point, and a sweeping signal is applied to the detection laser; the reflection spectrum of the optical resonant cavity is observed, and then the output frequency of the RF source is adjusted to move the resonance peak generated by the first-order sideband to the median point of the sweeping signal, and then the signal detected by the third photodetector is output to the third frequency detector and phase detector to mix with the demodulation signal and demodulate the error signal, which is then transmitted to the third PI controller after passing through the third low-pass filter to generate a feedback control signal, and the control signal is finally transmitted to the detection laser frequency tuning port to achieve laser frequency locking.

[0009] Furthermore, a piezoelectric ceramic is attached to one of the cavity mirrors of the optical resonant cavity, and the cavity length of the optical resonant cavity can be adjusted by adjusting the piezoelectric ceramic.

[0010] The present invention also provides a frequency stabilization method for a laser arbitrary detuned frequency device, comprising the following steps:

[0011] Step 1: Stabilize the pump laser frequency at the atomic resonance point by using the saturation absorption frequency stabilization method;

[0012] Step 2: using the pump light after frequency stabilization as a reference, multiplexing the modulation information carried by the pump light after saturation absorption and frequency stabilization, demodulating the error signal, and thus locking the cavity length of the optical resonant cavity;

[0013] Step 3: Use Bias Tee to superimpose two modulation signals of different frequencies, apply dual-phase modulation to the detection laser through the electro-optical phase modulator, demodulate a stable error signal while generating the modulation sideband, and then lock the first-order sideband on the longitudinal mode of the optical resonant cavity close to the optimal detuning point. By adjusting the first-order sideband frequency, continuous frequency tuning is achieved during the frequency stabilization process of the detection laser, so that the detection laser frequency can be accurately tuned to the optimal frequency detuning point while ensuring frequency stability.

[0014] The beneficial effects of the present invention compared with the prior art are:

[0015] The present invention can achieve frequency stabilization at any detuned frequency point of the laser within its frequency tuning range, and obtain frequency stability comparable to the atomic resonance frequency. By locking the optical resonant cavity with the pumping light inherent in the atomic spin inertial measurement system as a reference, resource reuse can be achieved. No additional modulation device is required during the optical resonant cavity locking process. In addition, a small-volume commercial optical resonant cavity can be used without considering its stability, thereby reducing both volume and cost. The dual-phase modulation frequency locking technology designed by the present invention uses Bias Tee to superimpose two modulation signals, and only uses a single EOM (electro-optical phase modulator) to achieve dual-phase modulation of the light beam, so that the error signal can be demodulated while generating the modulation sideband, thereby further reducing the volume and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the laser arbitrary detuned frequency stabilization device of the present invention;

[0017] The meanings of the reference numerals are as follows: 1 is a pumping laser, 2 is a first optical isolator, 3 is a first half-wave plate, 4 is a first polarization beam splitter prism, 5 is a first photodetector, 6 is a 50:50 reflector, 7 is an atomic gas chamber, 8 is a first reflector, 9 is a power divider, 10 is a first signal generator, 11 is a first frequency and phase detector, 12 is a first low-pass filter, 13 is a first PI controller, 14 is a second reflector, 15 is a second half-wave plate, 16 is a second polarization beam splitter prism, 17 is a first quarter-wave plate, 18 is a second photodetector. detector, 19 is a phase shifter, 20 is a second frequency detector, 21 is a second low-pass filter, 22 is a second PI controller, 23 is a detection laser, 24 is a second optical isolator, 25 is a third half-wave plate, 26 is an electro-optical phase modulator, 27 is a third polarization beam splitter, 28 is a second quarter-wave plate, 29 is a dichroic mirror, 30 is a convex lens, 31 is an optical resonant cavity, 32 is a piezoelectric ceramic, 33 is a third photodetector, 34 is a third frequency detector, 35 is an EOM drive, 36 is a radio frequency source, 37 is a Bias Tee, 38 is a radio frequency amplifier, 39 is a second signal generator, 40 is a third low-pass filter, 41 is a third PI controller, and 42 is an adder. DETAILED DESCRIPTION

[0018] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0019] The present invention is further described below with reference to the accompanying drawings and specific implementation examples.

[0020] like Figure 1 As shown, a laser arbitrary detuned frequency stabilization device of the present invention comprises a pumping laser atomic resonance point frequency stabilization optical path, an optical resonant cavity locking optical path and a detection laser arbitrary detuned frequency stabilization optical path. The pumping light atomic resonance point frequency stabilization optical path is used to lock the pumping light frequency to the atomic resonance point, the optical resonant cavity locking optical path uses the stabilized pumping light as the frequency standard, and locks the cavity length of the optical resonant cavity to the pumping light, and finally, the detection laser arbitrary detuned frequency stabilization optical path locks the detection laser to the optical resonant cavity.

[0021] The pumping laser atomic resonance point frequency stabilization optical path includes a pumping laser 1, a first optical isolator 2, a first half-wave plate 3, a first polarization beam splitter prism 4, a 50:50 transflector 6, an atomic gas chamber 7, a first reflector 8, a first photodetector 5, a first signal generator 10, a first frequency and phase detector 11, a first low-pass filter 12, a first PI controller 13, and a power divider 9.

[0022] The optical resonant cavity locking optical path includes a second reflector 14, a second half-wave plate 15, a second polarization beam splitter prism 16, a first quarter-wave plate 17, a dichroic mirror 29, a convex lens 30, an optical resonant cavity 31, a piezoelectric ceramic 32, a second photodetector 18, a phase shifter 19, a second frequency detector 20, a second low-pass filter 21, and a second PI controller 22;

[0023] The frequency stabilization optical path for detecting arbitrary detuned frequency of laser includes: a detection laser 23, a second optical isolator 24, a third half-wave plate 25, an electro-optical phase modulator (EOM) 26, a third polarization beam splitter prism 27, a second quarter-wave plate 28, a third photodetector 33, a third frequency and phase detector 34, a second signal generator 39, a radio frequency source 36, a radio frequency amplifier 38, a Bias Tee 37, an EOM driver 35, a third low-pass filter 40, a third PI controller 41, and an adder 42.

[0024] Among them, the pumping laser 1 with a central wavelength of 770nm passes through the first optical isolator 2, and is divided into two parts through the first half-wave plate 3 and the first polarization splitter prism 4: the reflected part enters the 50:50 reflector 6 and then is reflected into the potassium atomic gas chamber 7 as the pump light, and the pump light is reflected back to the potassium atomic gas chamber by the first reflector 8 as the detection light. The pump light and the detection light intersect to generate a saturated absorption spectrum, and the detection light carrying the spectrum information passes through the 50:50 reflector 6 and is detected by the first photodetector 5. The first signal generator 10 generates a sawtooth wave sweep signal with a frequency of 10 Hz and an amplitude of 5V and a modulation signal with a frequency of 30kHz and an amplitude of 40 mV, and then inputs them into the power divider 9. One end of the power divider 9 is connected to the pumping laser 1, and the other end is connected to the phase shifter 19. The first signal generator 10 simultaneously generates a demodulation signal with a frequency of 30 kHz and inputs it into the first frequency detector 11. The signal detected by the first photodetector 5 is output to the first frequency detector 11 to mix with the demodulation signal and demodulate an error signal. After passing through the first low-pass filter 12, it is transmitted to the first PI controller 13 and generates a feedback control signal. The control signal is finally transmitted to the pump laser frequency tuning port to achieve laser frequency locking.

[0025] The part transmitted by the first polarization beam splitter 4 is reflected by the second reflector 14, and then sequentially passes through the second half-wave plate 15, the second polarization beam splitter prism 16, the first quarter-wave plate 17, the dichroic mirror 29 and the convex lens 30, and then is coupled into the optical resonant cavity 31. The reflected light containing the phase information of the resonant cavity will return along the original optical path, sequentially pass through the convex lens 30 and the dichroic mirror 29, and then is reflected by the second polarization beam splitter prism 16 and enters the second photodetector 18. The signal at the other end of the power divider 9 can be regarded as a demodulated signal after passing through the phase shifter 19, and then is sent to the second frequency detector 20. The signal detected by the second photodetector 18 is output to the second frequency detector 20, mixed with the demodulated signal, and demodulated to obtain an error signal. After passing through the second low-pass filter 21, it is transmitted to the second PI controller 22 and generates a feedback control signal, which is then transmitted to the port of the piezoelectric ceramic 32 of the optical resonant cavity to achieve cavity length locking of the optical resonant cavity.

[0026] The laser light from the detection laser 23 with a central wavelength of 795 nm passes through the second optical isolator 24, and then passes through the third half-wave plate 25, the electro-optic phase modulator (EOM) 26, the third polarization beam splitter prism 27, and the second quarter-wave plate 28, and is reflected by the dichroic mirror 29, and then passes through the convex lens 30 and is coupled into the optical resonant cavity 31. The reflected light containing the phase information of the resonant cavity will return along the original optical path, pass through the convex lens 30, and is reflected by the dichroic mirror 29 into the third polarization beam splitter prism 27, and is reflected by it into the third photodetector 33. The RF source 36 generates a frequency of =500 MHz high frequency modulation signal with power of 7dbm is output to the RF port of Bias Tee 37, and the second signal generator 39 generates a frequency of =30 MHz, a relatively low-frequency modulation signal with an amplitude of 100 mV is amplified by the RF amplifier 38 and then output to the DC port of the Bias Tee 37. The RF&DC port of the Bias Tee 37 is connected to the EOM driver 35, and then the electro-optical phase modulator 26 is driven to apply dual-phase modulation to the detection laser. The detection laser frequency is tuned to the optimal detuning point, and the second signal generator 39 generates a sawtooth wave signal and applies it to the detection laser through the adder 42. Observe the reflection spectrum of the optical resonant cavity 31, and then adjust the output frequency of the RF source 36 to move the resonance peak generated by the first-order sideband to the midpoint of the swept signal. Then, the signal detected by the third photodetector 33 is output to the third frequency detector 34, mixed with the demodulation signal, and demodulated to obtain an error signal. After passing through the third low-pass filter 40, it is transmitted to the third PI controller 41 and generates a feedback control signal. The control signal is finally transmitted to the frequency tuning port of the detection laser to achieve laser frequency locking.

[0027] Therefore, a method for stabilizing the frequency of a laser with arbitrary detuned frequency according to an embodiment of the present invention comprises the following steps:

[0028] Step 1: Stabilize the pump laser frequency at the atomic resonance point by using the saturation absorption frequency stabilization method;

[0029] Step 2: using the pump light after frequency stabilization as a reference, multiplexing the modulation information carried by the pump light after saturation absorption and frequency stabilization, demodulating the error signal, and thus locking the cavity length of the optical resonant cavity;

[0030] Step 3: Use Bias Tee to superimpose two modulation signals of different frequencies, apply dual-phase modulation to the detection laser through the electro-optical phase modulator, demodulate a stable error signal while generating the modulation sideband, and then lock the first-order sideband on the longitudinal mode of the optical resonant cavity close to the optimal detuning point. By adjusting the first-order sideband frequency, continuous frequency tuning is achieved during the frequency stabilization process of the detection laser, so that the detection laser frequency can be accurately tuned to the optimal frequency detuning point while ensuring frequency stability.

[0031] Specifically, the step one includes:

[0032] After the pump laser 1 with a central wavelength of 770nm passes through the first optical isolator 2, it is divided into two parts through the first half-wave plate 3 and the first polarization beam splitter prism 4: the reflected part enters the 50:50 reflector 6 and then is reflected into the potassium atomic gas chamber 7 as the pump light, and the pump light is reflected back to the potassium atomic gas chamber by the first reflector 8 as the detection light. The pump light and the detection light intersect to generate a saturated absorption spectrum, and the detection light carrying the spectrum information passes through the 50:50 reflector 6 and is detected by the first photodetector 5. The first signal generator 10 generates a sawtooth wave sweep signal with a frequency of 10 Hz and an amplitude of 5V and a modulation signal with a frequency of 30 kHz and an amplitude of 40 mV, and then inputs them into the power divider 9. One end of the power divider 9 is connected to the pump laser 1, and the other end is connected to the phase shifter 19. The first signal generator 10 simultaneously generates a demodulation signal with a frequency of 30 kHz and inputs it into the first frequency detector 11. The signal detected by the first photodetector 5 is output to the first frequency detector 11 to mix with the demodulation signal and demodulate an error signal. After passing through the first low-pass filter 12, it is transmitted to the first PI controller 13 and generates a feedback control signal. The control signal is finally transmitted to the pump laser frequency tuning port to achieve laser frequency locking.

[0033] Specifically, the step 2 includes:

[0034] The part transmitted by the first polarization beam splitter 4 is reflected by the second reflector 14, and then sequentially passes through the second half-wave plate 15, the second polarization beam splitter prism 16, the first quarter-wave plate 17, the dichroic mirror 29 and the convex lens 30, and then is coupled into the optical resonant cavity 31. The reflected light containing the phase information of the resonant cavity will return along the original optical path, sequentially pass through the convex lens 30 and the dichroic mirror 29, and then is reflected by the second polarization beam splitter prism 16 and enters the second photodetector 18. The signal at the other end of the power divider 9 can be regarded as a demodulated signal after passing through the phase shifter 19, and then is sent to the second frequency detector 20. The signal detected by the second photodetector 18 is output to the second frequency detector 20, mixed with the demodulated signal, and demodulated to obtain an error signal. After passing through the second low-pass filter 21, it is transmitted to the second PI controller 22 and generates a feedback control signal, which is then transmitted to the port of the piezoelectric ceramic 32 of the optical resonant cavity to achieve cavity length locking of the optical resonant cavity.

[0035] Specifically, the step three includes: the laser light from the detection laser 23 with a central wavelength of 795nm passes through the second optical isolator 24, and then passes through the third half-wave plate 25, the electro-optic phase modulator (EOM) 26, the third polarization beam splitter prism 27, and the second quarter-wave plate 28, and then is reflected by the dichroic mirror 29, and then passes through the convex lens 30 and is coupled into the optical resonant cavity 31. The reflected light containing the phase information of the resonant cavity will return along the original optical path, pass through the convex lens 30, and is reflected by the dichroic mirror 29 into the third polarization beam splitter prism 27, and is reflected by it into the third photodetector 33. The RF source 36 generates a frequency of =500 MHz high frequency modulation signal with power of 7dbm is output to the RF port of Bias Tee 37, and the second signal generator 39 generates a frequency of =30 MHz, a relatively low-frequency modulation signal with an amplitude of 100 mV is amplified by the RF amplifier 38 and then output to the DC port of the Bias Tee 37. The RF&DC port of the Bias Tee 37 is connected to the EOM driver 35, and then the electro-optical phase modulator 26 is driven to apply dual-phase modulation to the detection laser. The detection laser frequency is tuned to the optimal detuning point, and a sweep signal is applied to the detection laser. The reflection spectrum of the optical resonator 31 is observed, and the output frequency of the RF source 36 is adjusted to move the resonance peak generated by the first-order sideband to the midpoint of the sweep signal. Then, the signal detected by the third photodetector 33 is output to the third frequency detector 34, mixed with the demodulation signal, and the error signal is demodulated. After passing through the third low-pass filter 40, it is transmitted to the third PI controller 41 and a feedback control signal is generated. The control signal is finally transmitted to the frequency tuning port of the detection laser to achieve laser frequency locking.

[0036] Preferably, in step 2, a piezoelectric ceramic 32 is attached to one of the cavity mirrors of the optical resonant cavity 31, and the cavity length of the optical resonant cavity can be adjusted by adjusting the piezoelectric ceramic 32. The dichroic mirror 29 is used to distinguish between the pumping laser and the detection laser, and the pumping light with a wavelength of 770nm can pass through the dichroic mirror 29, and the detection light with a wavelength of 795nm will be reflected by the dichroic mirror 29. The pumping laser coupled into the optical resonant cavity 31 contains the same modulation information as in step 1, so in the process of locking the cavity length of the optical resonant cavity 31, the modulation information can be used to demodulate the error signal without applying additional modulation to the resonant cavity.

[0037] Preferably, in step 3, the tuning bandwidth of the RF source 36 needs to cover at least half of the free spectrum range to achieve frequency stabilization at any frequency point. The DC port of the Bias Tee 37 will attenuate the power of the higher frequency signal, so the second signal generator 39 needs to be connected to the DC port of the Bias Tee 37 after amplifying the power through the RF amplifier 38. The high frequency signal and frequency are The low-frequency signals are superimposed without generating sum frequency signals and difference frequency signals. By adjusting the frequency of the RF source output signal, the detection laser locking frequency can be tuned.

[0038] The contents not described in detail in this specification belong to the prior art known to the professionals in this field.

Claims

1. A laser arbitrary detuning frequency stabilization device, characterized in that: It includes a pumping laser atomic resonance point frequency stabilization optical path, an optical resonant cavity locking optical path and a detection laser arbitrary detuned frequency stabilization optical path; the pumping light atomic resonance point frequency stabilization optical path is used to lock the pumping light frequency to the atomic resonance point, the optical resonant cavity locking optical path uses the stabilized pumping light as the frequency standard, and locks the cavity length of the optical resonant cavity to the pumping light; the detection laser arbitrary detuned frequency stabilization optical path locks the detection laser to the optical resonant cavity.

2. The laser arbitrary detuning frequency stabilization device according to claim 1, characterized in that: The pumping laser atomic resonance point frequency stabilization optical path comprises a pumping laser, a first optical isolator, a first half-wave plate, a first polarization beam splitter, a 50:50 reflective mirror, an atomic gas chamber, a first reflector, a first photodetector, a first signal generator, a first frequency detector, a first low-pass filter, a first PI controller, and a power divider; after the pumping laser with a central wavelength of 770 nm passes through the first optical isolator, it is divided into two parts through the first half-wave plate and the first polarization beam splitter: the reflected part enters the 50:50 reflective mirror and then is reflected into the potassium atomic gas chamber to generate pump light, the pump light is reflected back to the potassium atomic gas chamber by the first reflector and then serves as detection light, the pump light and the detection light intersect to generate a saturated absorption spectrum, and the detection light carrying spectral information passes through the 50:50 reflective mirror and is detected by the first photodetector; the first signal generator generates a sweep frequency signal and a frequency of The modulated signal is then input into the power divider, one end of the power divider is connected to the pump laser, and the other end is connected to the phase shifter; the first signal generator simultaneously generates a frequency of The demodulated signal is input to the first frequency detector, the signal detected by the first photodetector is output to the first frequency detector, mixed with the demodulated signal and demodulated to obtain an error signal, which is then transmitted to the first PI controller after passing through the first low-pass filter and generates a feedback control signal, and the control signal is finally transmitted to the pump laser frequency tuning port to achieve laser frequency locking.

3. The laser arbitrary detuning frequency stabilization device according to claim 1, characterized in that: The optical resonant cavity locking optical path comprises a second reflector, a second half-wave plate, a second polarization beam splitter prism, a first quarter-wave plate, a dichroic mirror, a convex lens, an optical resonant cavity, a piezoelectric ceramic, a second photodetector, a phase shifter, a second frequency detector, a second low-pass filter, and a second PI controller; the part transmitted by the first polarization beam splitter prism is reflected by the second reflector, and then sequentially passes through the second half-wave plate, the second polarization beam splitter prism, the first quarter-wave plate, the dichroic mirror, and the convex lens to be coupled into the optical resonant cavity, and the reflector containing the phase information of the resonant cavity is The emitted light will return along the original optical path, pass through the convex lens and the dichroic mirror in turn, and then be reflected by the second polarization splitter prism into the second photodetector; the signal at the other end of the power divider is regarded as a demodulated signal after passing through the phase shifter, and then sent to the second frequency detector and phase detector, and the signal detected by the second photodetector is output to the second frequency detector and mixed with the demodulated signal to demodulate the error signal, which is transmitted to the second PI controller after passing through the second low-pass filter and generates a feedback control signal, which is then transmitted to the port of the piezoelectric ceramic 32 of the optical resonant cavity to achieve cavity length locking of the optical resonant cavity.

4. The laser arbitrary detuning frequency stabilization device according to claim 1, characterized in that: The detection laser arbitrary detuned frequency stabilization optical path comprises a detection laser, a second optical isolator, a third half-wave plate, an electro-optical phase modulator, a third polarization beam splitter prism, a second quarter-wave plate, a third photodetector, a third frequency and phase detector, a second signal generator, a radio frequency source, a radio frequency amplifier, a bias tee, an EOM driver, a third low-pass filter, a third PI controller, and an adder; the laser light from the detection laser with a central wavelength of 795 nm passes through the second optical isolator, and then passes through the third half-wave plate, the electro-optical phase modulator, the third polarization beam splitter prism, and the second quarter-wave plate in sequence, and then is reflected by the dichroic mirror, and then is coupled into the optical resonant cavity through a convex lens, and the reflected light containing the phase information of the resonant cavity will return along the original optical path, and after passing through the convex lens, it will be reflected by the dichroic mirror into the third polarization beam splitter prism, and then reflected by the dichroic mirror into the third photodetector; the radio frequency source generates a frequency of The high frequency modulation signal is output to the RF port of the Bias Tee, and the second signal generator generates a frequency of The relatively low-frequency modulation signal is amplified by the RF amplifier and then output to the DC port of the Bias Tee. The RF&DC port of the Bias Tee is connected to the EOM driver, which then drives the electro-optic phase modulator to apply dual-phase modulation to the detection laser. Tuning the detection laser frequency to an optimal detuning point, and applying a frequency sweep signal to the detection laser; Observe the reflection spectrum of the optical resonant cavity, and then adjust the output frequency of the RF source to move the resonance peak generated by the first-order sideband to the median point of the swept frequency signal. Then, the signal detected by the third photodetector is output to the third frequency detector and phase detector to mix with the demodulated signal and demodulate the error signal. After passing through the third low-pass filter, it is transmitted to the third PI controller to generate a feedback control signal. The control signal is finally transmitted to the detection laser frequency tuning port to achieve laser frequency locking.

5. The laser arbitrary detuning frequency stabilization device according to claim 1, characterized in that: The optical resonant cavity has a piezoelectric ceramic attached to one of the cavity mirrors, and the cavity length of the optical resonant cavity is adjusted by adjusting the piezoelectric ceramic.

6. A frequency stabilization method for a laser arbitrary detuning frequency device according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Stabilize the pump laser frequency at the atomic resonance point by using the saturation absorption frequency stabilization method; Step 2: using the pump light after frequency stabilization as a reference, multiplexing the modulation information carried by the pump light after saturation absorption and frequency stabilization, demodulating the error signal, and thus locking the cavity length of the optical resonant cavity; Step 3: Use Bias Tee to superimpose two modulation signals of different frequencies, apply dual-phase modulation to the detection laser through the electro-optical phase modulator, demodulate a stable error signal while generating the modulation sideband, and then lock the first-order sideband on the longitudinal mode of the optical resonant cavity close to the optimal detuning point. By adjusting the first-order sideband frequency, continuous frequency tuning is achieved during the frequency stabilization process of the detection laser, so that the detection laser frequency can be accurately tuned to the optimal frequency detuning point while ensuring frequency stability.

7. The frequency stabilization method according to claim 6, characterized in that: The step one comprises: The pump laser with a central wavelength of 770nm passes through the first optical isolator, and is then divided into two parts by the first half-wave plate and the first polarization beam splitter prism: the reflected part enters the 50:50 reflector and then is reflected into the potassium atomic gas chamber to generate pump light, and the pump light is reflected back to the potassium atomic gas chamber by the first reflector as detection light. The pump light and the detection light intersect to generate a saturated absorption spectrum, and the detection light carrying spectral information passes through the 50:50 reflector and is detected by the first photodetector; the first signal generator generates a sweep frequency signal and a frequency of The modulated signal is then input into the power divider, one end of the power divider is connected to the pump laser, and the other end is connected to the phase shifter; the first signal generator simultaneously generates a frequency of The demodulated signal is input to the first frequency detector, the signal detected by the first photodetector is output to the first frequency detector, mixed with the demodulated signal and demodulated to obtain an error signal, which is then transmitted to the first PI controller after passing through the first low-pass filter and generates a feedback control signal, and the control signal is finally transmitted to the pump laser frequency tuning port to achieve laser frequency locking.

8. The frequency stabilization method according to claim 7, characterized in that: The second step comprises: The part transmitted by the first polarization beam splitter is reflected by the second reflector, and then passes through the second half-wave plate, the second polarization beam splitter, the first quarter-wave plate, the dichroic mirror and the convex lens in sequence to be coupled into the optical resonant cavity. The reflected light containing the phase information of the resonant cavity will return along the original optical path, pass through the convex lens and the dichroic mirror in sequence, and then be reflected by the second polarization beam splitter prism into the second photodetector; the signal at the other end of the power divider is regarded as a demodulated signal after passing through the phase shifter, and then is sent to the second frequency detector and phase detector, and the signal detected by the second photodetector is output to the second frequency detector and phase detector for mixing with the demodulated signal and demodulating an error signal, which is transmitted to the second PI controller after passing through the second low-pass filter and generates a feedback control signal, and then is transmitted to the port of the piezoelectric ceramic 32 of the optical resonant cavity to achieve cavity length locking of the optical resonant cavity.

9. The frequency stabilization method according to claim 7, characterized in that: The step three comprises: The laser light from the detection laser with a central wavelength of 795nm passes through the second optical isolator, and then passes through the third half-wave plate, the electro-optic phase modulator, the third polarization beam splitter prism, and the second quarter-wave plate in sequence, and is reflected by the dichroic mirror, and then passes through the convex lens and is coupled into the optical resonant cavity. The reflected light containing the phase information of the resonant cavity will return along the original optical path, pass through the convex lens, be reflected by the dichroic mirror, enter the third polarization beam splitter prism, and be reflected by it into the third photodetector; the frequency generated by the RF source is The high frequency modulation signal is output to the RF port of the Bias Tee, and the second signal generator generates a frequency of A relatively low-frequency modulation signal is amplified by the RF amplifier and then output to the DC port of the Bias Tee. The RF&DC port of the Bias Tee is connected to the EOM driver, and then the electro-optical phase modulator is driven to apply dual-phase modulation to the detection laser; the detection laser frequency is tuned to the optimal detuning point, and a sweeping signal is applied to the detection laser; the reflection spectrum of the optical resonant cavity is observed, and then the output frequency of the RF source is adjusted to move the resonance peak generated by the first-order sideband to the median point of the sweeping signal, and then the signal detected by the third photodetector is output to the third frequency detector and phase detector to mix with the demodulation signal and demodulate the error signal, which is then transmitted to the third PI controller after passing through the third low-pass filter to generate a feedback control signal, and the control signal is finally transmitted to the detection laser frequency tuning port to achieve laser frequency locking.

10. The frequency stabilization method according to claim 9, characterized in that: In the step 3, the tuning bandwidth of the RF source covers at least half of the free spectrum range; the third signal generator is connected to the DC port of the BiasTee after the power is amplified by the RF amplifier; For a mixer, the Bias Tee will be The high frequency signal and frequency are The low-frequency signal is superimposed without generating sum frequency signal and difference frequency signal; by adjusting the frequency of the RF source output signal , to achieve the tuning of the detection laser locking frequency.

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