Laser frequency stabilization property evaluation system and method based on EIT phase noise spectrum

Abstract

This invention relates to the field of laser frequency stabilization technology, and discloses a system and method for evaluating the frequency stabilization properties of lasers based on the EIT phase noise spectrum. The system includes a probe light frequency stabilization unit, a first coupled light frequency stabilization unit, a second coupled light frequency stabilization unit, a first EIT spectral unit, a second EIT spectral unit, a third EIT spectral unit, a first coupled light phase detection feedback unit, a second coupled light phase detection feedback unit, a first noise evaluation unit, a second noise evaluation unit, and a third noise evaluation unit. This invention achieves accurate evaluation of the frequency stabilization properties of coupled lasers by utilizing the EIT phase noise spectrum to address frequency fluctuations under various frequency stabilization methods.

Description

Technical Field

[0001] This invention relates to the field of laser frequency stabilization technology, specifically to a laser frequency stabilization property evaluation system and method based on EIT phase noise spectrum. Background Technology

[0002] A Rydberg atom is an atom whose outermost electron is excited to a highly excited state (typically with a principal quantum number n ≥ 15). Compared to ground-state atoms, Rydberg atoms possess many unique properties: their radiative lifetime is proportional to n³, their electric dipole moment to n⁴, and their polarizability to n⁷, among others. These characteristics make Rydberg atoms an excellent physical platform for research in quantum storage, quantum computing, and quantum precision measurement.

[0003] Electromagnetically induced transparency (EIT) is the most widely used method for Rydberg atom detection. A weak probe beam excites an alkali metal atom from its ground state to an intermediate state, while a strong coupling beam excites the atom from the intermediate state to the desired Rydberg state. Locking the laser frequency to the corresponding atomic transition energy level is crucial for achieving precise Rydberg atom measurements. Current methods for EIT spectral-coupled laser frequency stabilization include modulation and demodulation, modulation-transfer spectroscopy (MTS), and two-color polarization spectroscopy. The first two methods inevitably introduce phase noise into the frequency stabilization module.

[0004] In the EIT medium, both the phase noise of the probe field and the coupling field can be converted into intensity noise of the probe field. Therefore, the phase noise introduced by the frequency stabilization module will affect the signal-to-noise ratio of the EIT spectrum of the measurement module, and thus affect the measurement accuracy. However, existing frequency stabilization evaluation methods only evaluate the frequency fluctuations in the time and frequency domains under different coupled laser frequency stabilization methods, ignoring whether various coupled laser frequency stabilization methods will introduce noise into the EIT spectrum of the measurement module. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a laser frequency stabilization property evaluation system and method based on EIT phase noise spectrum. By fully considering various frequency locking methods, the system evaluates the frequency stabilization property of the laser, thereby improving the accuracy of the laser frequency stabilization property evaluation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a laser frequency stabilization property evaluation system based on EIT phase noise spectrum, comprising a probe light frequency stabilization unit, a first coupled light frequency stabilization unit, a second coupled light frequency stabilization unit, a first EIT spectral unit, a second EIT spectral unit, a third EIT spectral unit, a first coupled light phase detection feedback unit, a second coupled light phase detection feedback unit, a first noise evaluation unit, a second noise evaluation unit, and a third noise evaluation unit; the first EIT spectral unit and the first coupled light phase detection feedback unit form the first coupled light frequency stabilization unit, and the second EIT spectral unit and the second coupled light phase detection feedback unit form the second coupled light frequency stabilization unit;

[0007] The light output from the probe laser generator is split into three beams after passing through the probe light beam splitting unit. One beam is stabilized by the probe light frequency stabilization unit to stabilize the frequency of the probe laser generator. Another beam is sent to the first EIT spectral unit or the second EIT spectral unit. The third beam is sent to the third EIT spectral unit.

[0008] The light output from the coupled laser generator is split into two beams after passing through the coupled light beam splitting unit. One beam is sent to the third EIT spectral unit, and the other beam is sent to the first EIT spectral unit or the second EIT spectral unit.

[0009] The third EIT spectral unit is used to generate EIT spectra and send them to the third noise evaluation unit; the first EIT spectral unit and the second EIT spectral unit are used to generate EIT spectra respectively, and the generated EIT spectra are divided into two parts, one part of which is sent to the first noise evaluation unit or the second noise evaluation unit, and the other part is used to lock the light output by the coupled laser generator after passing through the first coupled light phase detection feedback unit or the second coupled light phase detection feedback unit.

[0010] The first coupled optical frequency stabilization unit is a modulation and demodulation frequency stabilization unit, and the second coupled optical frequency stabilization unit is a modulation transfer spectrum frequency stabilization unit.

[0011] In the first coupling light frequency stabilization unit, the sinusoidal signal output by the lock-in amplifier is applied to the piezoelectric ceramic voltage of the coupling laser generator as a modulation signal; the probe laser is split into two beams and incident in the same direction into the atomic gas cell, and the coupling laser and one of the probe laser beams coincide in opposite directions in the atomic gas cell. The two probe laser beams are detected by the first balanced photodetector (21), and then a part of the electrical signal obtained by the first balanced photodetector (21) is input into the lock-in amplifier for demodulation to generate a differential error signal. Then the differential error signal is input into the PI circuit, and the PI controller feeds back to the piezoelectric ceramic voltage of the coupling laser generator to lock it. The other part of the electrical signal is sent to the first noise evaluation unit.

[0012] In the second coupling light frequency stabilization unit, the probe laser is split into two beams and incident in the same direction into the atomic gas cell. After the frequency stabilization coupling laser is phase modulated by the electro-optic modulator, it coincides with one of the probe laser beams in the opposite direction in the atomic gas cell. The unmodulated probe light undergoes a four-wave mixing effect in the nonlinear medium, generating a sideband of the probe light, which then transfers the sideband of the coupling light onto the probe light. The two probe laser beams are detected by the second balanced photodetector (31) to obtain the beat frequency signal of the probe light and its sideband. A portion of the electrical signal obtained by the first balanced photodetector (21) is input into the mixer and the modulation signal of the electro-optic modulator for demodulation and filtering to obtain the modulation transfer spectrum signal. Then, the modulation transfer spectrum signal is fed back to the piezoelectric ceramic voltage of the coupling laser generator by the PI controller to lock it. The other portion of the electrical signal is sent to the second noise evaluation unit.

[0013] The first noise evaluation unit and the second noise evaluation unit are spectrum analyzers.

[0014] The probe laser frequency stabilization unit is a saturated absorption spectral frequency stabilization unit.

[0015] The first noise evaluation unit, the second noise evaluation unit, and the third noise evaluation unit use phase noise spectrum technology, which converts phase noise into intensity noise, to perform EIT spectrum noise evaluation.

[0016] Furthermore, this invention also provides a method for evaluating the frequency stabilization properties of lasers based on the EIT phase noise spectrum, implemented using the aforementioned system for evaluating the frequency stabilization properties of lasers based on the EIT phase noise spectrum, comprising the following steps:

[0017] Step 1: Send the light output from the probe laser generator to the first EIT spectral unit, and at the same time, send the light output from the coupling laser generator to the first EIT spectral unit;

[0018] Step 2: Using the spectrum output by the first EIT spectral unit, a feedback signal is generated by the first coupling light phase detection feedback unit to lock the frequency of the coupled laser generator. At the same time, the laser phase noise spectrum is obtained by the first noise evaluation unit and the third noise evaluation unit respectively. Based on the obtained laser phase noise spectrum, it is determined whether phase noise has been introduced during the frequency stabilization process.

[0019] Step 3: Send the light output from the probe laser generator to the second EIT spectral unit, and at the same time, send the light output from the coupling laser generator to the second EIT spectral unit;

[0020] Step 4: Using the spectrum output by the second EIT spectral unit, a feedback signal is generated by the second coupled light phase detection feedback unit to lock the frequency of the coupled laser generator. At the same time, the laser phase noise is acquired by the second noise evaluation unit and the third noise evaluation unit respectively. Based on the acquired laser phase noise spectrum, it is determined whether phase noise has been introduced during the frequency stabilization process.

[0021] Step 5: Based on the results of Step 2 and Step 4, comprehensively evaluate the frequency stabilization properties of the coupled light generator.

[0022] In steps 2 and 4, the setting parameters of the third noise evaluation unit are the same.

[0023] Compared with the prior art, the present invention has the following advantages: The present invention provides a laser frequency stabilization property evaluation system and method based on EIT phase noise spectrum. In the modulation and demodulation frequency stabilization unit, the signal generated by the first EIT spectral unit is connected to the first noise evaluation unit, and the signal generated by the third EIT spectral unit is connected to the third noise evaluation unit; in the modulation and transfer spectral frequency stabilization unit, the signal generated by the second EIT spectral unit is connected to the second noise evaluation unit, and the signal generated by the third EIT spectral unit is connected to the third noise evaluation unit. Through the frequency fluctuations under various frequency stabilization methods, the frequency stabilization property of the coupled laser is accurately evaluated using the EIT phase noise spectrum. Attached Figure Description

[0024] Figure 1 A schematic diagram of the device structure used in a laser frequency stabilization property evaluation method based on EIT phase noise spectrum provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of one of the coupled laser frequency stabilization units provided in an embodiment of the present invention: a modulation and demodulation frequency stabilization unit; wherein the dashed box contains a schematic diagram of the structure of the third EIT spectral unit;

[0026] Figure 3 A schematic diagram of the structure of another coupled laser frequency stabilization unit provided in this embodiment of the invention: a modulation transfer spectrum frequency stabilization unit; wherein the dashed box is a schematic diagram of the structure of the third EIT spectrum unit;

[0027] Figure 4 The phase noise analysis diagrams obtained by the first noise evaluation unit and the third noise evaluation unit under the modulation and demodulation unit in the embodiments of the present invention are shown below.

[0028] Figure 5 The phase noise analysis diagrams obtained by the second noise evaluation unit and the third noise evaluation unit under the MTS unit with zero frequency sweep detection are provided in the embodiments of the present invention.

[0029] Figure 6The phase noise of the first EIT spectral unit and the third EIT spectral unit under the modulation and demodulation unit provided in the embodiments of the present invention varies with the modulation amplitude;

[0030] Figure 7 The phase noise of the second EIT spectral unit provided in this embodiment of the invention varies with the modulation amplitude. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, this embodiment of the invention provides a laser frequency stabilization property evaluation system based on EIT phase noise spectrum, including a probe light frequency stabilization unit, a first coupled light frequency stabilization unit, a second coupled light frequency stabilization unit, a first EIT spectral unit, a second EIT spectral unit, a third EIT spectral unit, a first coupled light phase detection feedback unit, a second coupled light phase detection feedback unit, a first noise evaluation unit, a second noise evaluation unit, and a third noise evaluation unit; the first EIT spectral unit and the first coupled light phase detection feedback unit form the first coupled light frequency stabilization unit, and the second EIT spectral unit and the second coupled light phase detection feedback unit form the second coupled light frequency stabilization unit.

[0034] In this embodiment, the 852nm laser output from the probe laser generator is split into three beams by the probe light beam splitting unit. One beam is stabilized by the probe light frequency stabilization unit, another beam is sent to the first EIT spectral unit or the second EIT spectral unit, and the third beam is sent to the third EIT spectral unit. The 509nm laser output from the coupling laser generator is split into two beams by the coupling light beam splitting unit. One beam is sent to the third EIT spectral unit, and the other beam is sent to the first EIT spectral unit or the second EIT spectral unit. The third EIT spectral unit is used to generate EIT spectra and send them to the third noise evaluation unit. The first and second EIT spectral units are used to generate EIT spectra, which are divided into two parts. One part is sent to the first noise evaluation unit or the second noise evaluation unit, and the other part is used to lock the light output from the coupling laser generator by the first coupling light phase detection feedback unit or the second coupling light phase detection feedback unit.

[0035] Specifically, in this embodiment, the probe light output by the probe laser generator 111 is divided into three paths after passing through the probe light beam splitting unit 112: path 1121 passes through the probe light frequency stabilization unit 113 to stabilize the probe light frequency through saturated absorption spectrum; path 1122 enters the first / second EIT spectral unit 126; and path 1123 enters the third EIT spectral unit 123. The coupled laser generator 121 is split into two paths after passing through the coupled light beam splitting unit 122: path 1221 enters the first / second EIT spectral unit 126. After both paths 1122 and 1221 enter the first / second EIT spectral unit 126, the first / second EIT spectral unit 126 is connected to a balanced photodetector and then split into two paths: path 1271 is connected to the first / second coupled light phase detection feedback unit 129 to achieve frequency stabilization of the coupled laser; path 1272 is connected to the first / second noise evaluation unit 128; path 1222 enters the third EIT spectral unit 123. After both paths 1123 and 1222 enter the third EIT spectral unit 123, this unit is connected to the third noise evaluation unit 125.

[0036] Furthermore, in this embodiment, the first coupled optical frequency stabilization unit is a modulation and demodulation frequency stabilization unit, and the second coupled optical frequency stabilization unit is a modulation transfer spectrum frequency stabilization unit.

[0037] like Figure 2 As shown, the first coupling light frequency stabilization unit in this embodiment is a modulation and demodulation frequency stabilization unit. The coupling laser generator is split into two beams by a coupling light beam splitting device composed of a half-wave plate and a polarizing beam splitter prism. One beam is sent to the third EIT spectral unit, and the other beam is used as the coupling laser for frequency stabilization. Furthermore, by changing the angle between the fast axis or slow axis of the half-wave plate and the polarization direction of the coupling laser, the light intensity of the 509nm wavelength coupling laser can be controlled.

[0038] like Figure 3 As shown, in this embodiment, a lock-in amplifier outputs a sinusoidal signal with a frequency of 52.5 kHz and an amplitude of 0.004 V, which is applied to the piezoelectric ceramic voltage of the coupled laser generator 121 as a modulation signal. The probe laser is split into two beams and incident in the same direction into the atomic gas chamber. The coupled laser and one of the probe laser beams coincide in opposite directions in the atomic gas chamber. The two probe laser beams are detected by the first balanced photodetector 21. Then, a part of the electrical signal obtained by the first balanced photodetector 21 is input into the lock-in amplifier for demodulation to generate a differential error signal. After passing through a low-pass filter (LPF), the differential error signal is input into the PI circuit. The PI controller feeds back the piezoelectric ceramic voltage of the coupled laser generator to lock it. The other part of the electrical signal is sent to the first noise evaluation unit.

[0039] Figure 2The dashed box in the diagram shows the third EIT spectral unit, which includes an atomic gas cell and a third balanced photodetector 33. In the third EIT spectral unit, the probe laser is split into two beams. One beam coincides with the coupling laser in opposite directions in the atomic gas cell, while the other beam passes directly through the atomic gas cell. The two probe beams are used to obtain the EIT spectrum by the third balanced photodetector 33 and then sent to the third noise evaluation unit.

[0040] like Figure 3 As shown, the second coupling light frequency stabilization unit in this embodiment is a modulation transfer spectrum frequency stabilization unit. Specifically, the coupling laser generator 121 is split into two beams by a coupling light beam splitting device composed of a half-wave plate and a polarizing beam splitter prism. One beam is sent to the third EIT spectrum unit to generate an EIT spectrum together with the probe light, and the other beam serves as the coupling laser for frequency stabilization. Furthermore, changing the angle between the fast axis or slow axis of the half-wave plate and the polarization direction of the coupling laser can achieve control of the light intensity of the 509nm wavelength coupling laser.

[0041] like Figure 3 As shown, in the second coupling light frequency stabilization unit, the probe laser is split into two beams and incident in the same direction into the atomic gas cell. The frequency stabilization coupling laser is phase-modulated by an electro-optic modulator driven by a modulation signal with a frequency of 10.3MHz and an amplitude of 1.0V. It then coincides with one of the probe laser beams in the atomic gas cell in the opposite direction. The unmodulated probe light undergoes a four-wave mixing effect in the nonlinear medium, generating a sideband of the probe light. This sideband of the coupling light is then transferred to the probe light. The two probe laser beams are detected by the second balanced photodetector 31 to obtain the beat frequency signal of the probe light and its sideband. A portion of the electrical signal obtained by the first balanced photodetector 21 is input into the mixer and the modulation signal of the electro-optic modulator for demodulation and filtering to obtain the modulation transfer spectrum signal. Then, after passing through a low-pass filter LPF and a PI controller, the modulation transfer spectrum signal is converted into a frequency discrimination signal and fed back to the piezoelectric ceramic voltage of the coupling laser generator for locking. The other portion of the electrical signal is sent to the second noise evaluation unit.

[0042] Figure 3 In the image, the dashed box shows the third EIT spectral unit, which includes an atomic gas cell and a third balanced photodetector 23.

[0043] Specifically, in this embodiment, the first noise evaluation unit, the second noise evaluation unit, and the third noise evaluation unit are all spectrum analyzers SA.

[0044] Specifically, in this embodiment, the probe laser frequency stabilization unit is a saturated absorption spectrum frequency stabilization unit.

[0045] Specifically, in this embodiment, the first noise evaluation unit, the second noise evaluation unit, and the third noise evaluation unit use phase noise spectrum technology, which converts phase noise into intensity noise, to perform EIT spectrum noise evaluation.

[0046] Example 2

[0047] Embodiment 2 of the present invention provides a method for evaluating the frequency stabilization properties of a laser based on the EIT phase noise spectrum, which is implemented based on the laser frequency stabilization property evaluation system based on the EIT phase noise spectrum described in Embodiment 1, and includes the following steps:

[0048] Step 1: Send the light output from the probe laser generator to the first EIT spectral unit, and at the same time, send the light output from the coupling laser generator to the first EIT spectral unit.

[0049] Step 2: Using the spectrum output by the first EIT spectral unit, a feedback signal is generated by the first coupling light phase detection feedback unit to lock the frequency of the coupled laser generator. At the same time, the laser phase noise spectrum is obtained by the first noise evaluation unit and the third noise evaluation unit respectively. Based on the obtained laser phase noise spectrum, it is determined whether phase noise has been introduced during the frequency stabilization process.

[0050] In this embodiment, the lock-in amplifier of the first coupling light phase detection feedback unit undertakes the modulation and demodulation task, generates the phase detection signal of the coupled laser, and feeds back the voltage of the phase detection signal of the coupled light to the coupled laser generator in real time to achieve frequency stabilization of the coupled laser.

[0051] Step 3: Send the light output from the probe laser generator to the second EIT spectral unit, and at the same time, send the light output from the coupling laser generator to the second EIT spectral unit;

[0052] Step 4: Using the spectrum output by the second EIT spectral unit, a feedback signal is generated by the second coupled light phase detection feedback unit to lock the frequency of the coupled laser generator. At the same time, the laser phase noise is obtained by the second noise evaluation unit and the third noise evaluation unit respectively. Based on the obtained laser phase noise spectrum, it is determined whether phase noise has been introduced during the frequency stabilization process.

[0053] In the second coupling light phase detection feedback unit of this embodiment, the modulated probe light and the modulation signal are mixed to generate a phase detection signal for the coupling laser, and the voltage of the phase detection signal of the coupling light is fed back to the coupling laser generator in real time to achieve frequency stabilization of the coupling laser.

[0054] Step 5: Based on the results of Step 2 and Step 4, comprehensively evaluate the frequency stabilization properties of the coupled light generator.

[0055] In steps 2 and 4, the setting parameters of the third noise evaluation unit are the same.

[0056] Specifically, step 2 further includes changing the modulation amplitude of the lock-in amplifier and repeating the measurement; step 4 further includes changing the modulation amplitude applied to the acousto-optic modulator EOM and repeating the measurement. During the above noise assessment, the spectrum analyzer is set to zero-sweep detection.

[0057] like Figure 4 The figure shows the laser phase noise analysis obtained by the zero-sweep frequency detection of the first noise evaluation unit and the third noise evaluation unit under the modulation and demodulation unit. Specifically, the balanced photodetector 21 is connected to the spectrum analyzer 22, and the balanced photodetector 23 is connected to the spectrum analyzer 24. The center frequency is set to 52.5kHz, the video bandwidth is 5.1Hz, the resolution bandwidth is 5.1Hz, and the sweep width is 0Hz. The black line represents the measurement result of the first noise evaluation unit, and the blue line represents the measurement result of the third noise evaluation unit. It can be seen that both curves are M-shaped. According to the EIT phase noise spectrum method, this means that both the frequency stabilization module and the measurement module have a phase noise to detector field intensity noise conversion. The measurement module, i.e., the third EIT spectrum unit, introduces phase noise into the EIT spectrum due to the modulation and demodulation frequency stabilization method.

[0058] like Figure 5 The image shows the laser phase noise analysis obtained from the zero-sweep frequency detection of the second noise evaluation unit and the third noise evaluation unit under the MTS unit. Specifically, the balanced photodetector 31 is connected to the spectrum analyzer 32, and the balanced photodetector 33 is connected to the spectrum analyzer 34. The center frequency is set to 10.3MHz, the video bandwidth to 10Hz, the resolution bandwidth to 100Hz, and the sweep width to 0Hz. The black line represents the measurement result of the second noise evaluation unit, and the blue line represents the measurement result of the third noise evaluation unit. It can be seen that only the black curve is M-shaped. According to the EIT phase noise spectrum method, this means that only the frequency stabilization module has the conversion of phase noise to detection field intensity noise. The measurement module, i.e., the third EIT spectrum unit, does not introduce phase noise into the EIT spectrum due to the MTS frequency stabilization method.

[0059] like Figure 6 As shown, the phase noise of the first EIT spectral unit and the third EIT spectral unit under modulation and demodulation varies with the modulation amplitude. Specifically, the first EIT spectral unit is shown as a black dot, and the third EIT spectral unit is shown as a blue dot. By changing the modulation amplitude of the lock-in amplifier, the zero-sweep frequency detection of the first and third noise evaluation units is repeated, and the average value of the maximum phase noise is taken as the evaluation point.

[0060] like Figure 7The figure shows the variation of phase noise of the second EIT spectral unit with modulation amplitude. Specifically, the EOM modulation amplitude is changed, and the zero-sweep frequency detection of the second noise evaluation unit is repeated, and the average value of the maximum phase noise is taken as the evaluation point.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser frequency stabilization property evaluation system based on EIT phase noise spectrum, characterized in that, It includes a probe light frequency stabilization unit, a first coupling light frequency stabilization unit, a second coupling light frequency stabilization unit, a first EIT spectral unit, a second EIT spectral unit, a third EIT spectral unit, a first coupling light phase detection feedback unit, a second coupling light phase detection feedback unit, a first noise evaluation unit, a second noise evaluation unit, and a third noise evaluation unit; the first EIT spectral unit and the first coupling light phase detection feedback unit form the first coupling light frequency stabilization unit, and the second EIT spectral unit and the second coupling light phase detection feedback unit form the second coupling light frequency stabilization unit; The light output from the probe laser generator is split into three beams after passing through the probe light beam splitting unit. One beam is stabilized by the probe light frequency stabilization unit to stabilize the frequency of the probe laser generator. Another beam is sent to the first EIT spectral unit or the second EIT spectral unit. The third beam is sent to the third EIT spectral unit. The light output from the coupled laser generator is split into two beams after passing through the coupled light beam splitting unit. One beam is sent to the third EIT spectral unit, and the other beam is sent to the first EIT spectral unit or the second EIT spectral unit. The third EIT spectral unit is used to generate EIT spectra and send them to the third noise evaluation unit; the first EIT spectral unit and the second EIT spectral unit are used to generate EIT spectra respectively, and the generated EIT spectra are divided into two parts, one part of which is sent to the first noise evaluation unit or the second noise evaluation unit, and the other part is used to lock the light output by the coupled laser generator after passing through the first coupled light phase detection feedback unit or the second coupled light phase detection feedback unit.

2. The laser frequency stabilization property evaluation system based on EIT phase noise spectrum according to claim 1, characterized in that, The first coupled optical frequency stabilization unit is a modulation and demodulation frequency stabilization unit, and the second coupled optical frequency stabilization unit is a modulation transfer spectrum frequency stabilization unit.

3. The laser frequency stabilization property evaluation system based on EIT phase noise spectrum according to claim 1, characterized in that, In the first coupling light frequency stabilization unit, the sinusoidal signal output by the lock-in amplifier is applied to the piezoelectric ceramic voltage of the coupling laser generator as a modulation signal; the probe laser is split into two beams and incident in the same direction into the atomic gas cell, and the coupling laser and one of the probe laser beams coincide in opposite directions in the atomic gas cell. The two probe laser beams are detected by the first balanced photodetector (21), and then a part of the electrical signal obtained by the first balanced photodetector (21) is input into the lock-in amplifier for demodulation to generate a differential error signal. Then the differential error signal is input into the PI circuit, and the PI controller feeds back to the piezoelectric ceramic voltage of the coupling laser generator to lock it. The other part of the electrical signal is sent to the first noise evaluation unit. In the second coupling light frequency stabilization unit, the probe laser is split into two beams and incident in the same direction into the atomic gas cell. After the frequency stabilization coupling laser is phase modulated by the electro-optic modulator, it coincides with one of the probe laser beams in the opposite direction in the atomic gas cell. The unmodulated probe light undergoes a four-wave mixing effect in the nonlinear medium, generating a sideband of the probe light, which then transfers the sideband of the coupling light onto the probe light. The two probe laser beams are detected by the second balanced photodetector (31) to obtain the beat frequency signal of the probe light and its sideband. A portion of the electrical signal obtained by the first balanced photodetector (21) is input into the mixer and the modulation signal of the electro-optic modulator for demodulation and filtering to obtain the modulation transfer spectrum signal. Then, the modulation transfer spectrum signal is fed back to the piezoelectric ceramic voltage of the coupling laser generator by the PI controller to lock it. The other portion of the electrical signal is sent to the second noise evaluation unit.

4. The laser frequency stabilization property evaluation system based on EIT phase noise spectrum according to claim 1, characterized in that, The first noise evaluation unit and the second noise evaluation unit are spectrum analyzers.

5. The laser frequency stabilization property evaluation system based on EIT phase noise spectrum according to claim 1, characterized in that, The probe light frequency stabilization unit is a saturated absorption spectrum frequency stabilization unit.

6. The laser frequency stabilization property evaluation system based on EIT phase noise spectrum according to claim 1, characterized in that, The first noise evaluation unit, the second noise evaluation unit, and the third noise evaluation unit use phase noise spectrum technology, which converts phase noise into intensity noise, to perform EIT spectrum noise evaluation.

7. A method for evaluating the frequency stabilization properties of a laser based on the EIT phase noise spectrum, implemented based on the laser frequency stabilization property evaluation system based on the EIT phase noise spectrum as described in any one of claims 1 to 4, characterized in that, The following steps are involved: Step 1: Send the light output from the probe laser generator to the first EIT spectral unit, and at the same time, send the light output from the coupling laser generator to the first EIT spectral unit; Step 2: Using the spectrum output by the first EIT spectral unit, a feedback signal is generated by the first coupling light phase detection feedback unit to lock the frequency of the coupled laser generator. At the same time, the laser phase noise spectrum is obtained by the first noise evaluation unit and the third noise evaluation unit respectively. Based on the obtained laser phase noise spectrum, it is determined whether phase noise has been introduced during the frequency stabilization process. Step 3: Send the light output from the probe laser generator to the second EIT spectral unit, and at the same time, send the light output from the coupling laser generator to the second EIT spectral unit; Step 4: Using the spectrum output by the second EIT spectral unit, a feedback signal is generated by the second coupled light phase detection feedback unit to lock the frequency of the coupled laser generator. At the same time, the laser phase noise is acquired by the second noise evaluation unit and the third noise evaluation unit respectively. Based on the acquired laser phase noise spectrum, it is determined whether phase noise has been introduced during the frequency stabilization process. Step 5: Based on the results of Step 2 and Step 4, comprehensively evaluate the frequency stabilization properties of the coupled laser generator.

8. The method for evaluating the frequency stabilization properties of a laser based on the EIT phase noise spectrum according to claim 7, characterized in that, In steps 2 and 4, the setting parameters of the third noise evaluation unit are the same.

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