A method of inverse double sideband super-stable cavity locking wide tuning

Abstract

The application relates to the technical field of optical measurement, in particular to a kind of anti-phase double sideband ultra-stable cavity locking wide tuning method.The method comprises the following steps: obtaining a target laser beam emitted by a target laser;after the target laser beam is input into a first modulator, a first intermediate laser beam is obtained;after the first intermediate laser beam is input into a second modulator, a second intermediate laser beam is obtained;after the second intermediate laser beam is input into a PDH optical path, a key laser beam is obtained;after the key laser beam is input into a target FP cavity, an actual frequency difference is obtained, and adjustment is carried out according to the actual frequency difference;it can be known that, compared with the prior art, by tuning the ultra-stable reference benchmark itself, and using sideband locking technology to let the target laser serve as a "driven device" to track the moving benchmark in real time, wide tuning in a large range can be achieved while maintaining and high stability, and the contradiction between stability and wide tuning is solved.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and in particular to an ultrastable cavity-locked wide-range tuning method with an anti-phase double-band. Background Technology

[0002] In the prior art, sideband locking is a technique that uses the sideband frequency generated by modulated laser as a "ruler" or "reference point" to stably lock the laser frequency to the resonant frequency of a certain optical reference cavity.

[0003] Ultrastable cavities are typically made of ultra-low expansion materials and placed in a vibration-isolated, temperature-controlled vacuum environment to maintain frequency stability, ensuring that the frequency hardly changes with the environment. However, by sideband locking the ultrastable cavity, lasers with extremely narrow linewidths, extremely high frequency stability, and wide tunability can be obtained. The resonant frequency of a Fabry-Perot (FP) cavity is not continuous but acts like a "frequency ruler," with only frequencies that meet specific resonance conditions remaining stable within it. The intervals between these frequencies (free spectral range, FSR) are fixed. Therefore, the laser can only be locked to these discrete frequency points. If the target frequency required by the user is not far from the resonant frequency of a certain FP cavity (e.g., within tens of MHz to 200 MHz), the traditional approach is to use an acousto-optic modulator (AOM). The AOM changes the refractive index through acoustic waves, precisely shifting the laser frequency by a fixed amount. In this way, the laser itself is locked to the resonance peak of the FP cavity. When the difference between the required frequency and the FP cavity resonant frequency exceeds several hundred MHz (e.g., 500 MHz or even 1 GHz), the frequency shifting capability of the AOM is insufficient to achieve compensation. In order to cover a larger frequency range, multiple AOMs with different center frequencies may need to be cascaded, which makes the system complex, bulky and lossy. Furthermore, when the AOM operates away from its design center frequency, the diffraction efficiency will be significantly reduced, resulting in optical power loss, which may lead to the deterioration of the performance of the ultrastable laser. Summary of the Invention

[0004] The purpose of this invention is to provide a wide-range tuning method for an anti-phase double-sideband ultrastable cavity, which can achieve continuous and precise frequency tuning from hundreds of MHz to several GHz. This method solves the problem of insufficient AOM bandwidth and avoids the problems of complex optical alignment, high insertion loss, and large system size caused by using multiple AOMs or wideband AOMs. It combines the ultra-high frequency stability of FP cavities (achieved through carrier locking) with the clean spectrum and wide-range tunability of electrical anti-phase double-sideband, which helps to realize the miniaturization and automated locking of ultrastable cavities and improves the practicality of ultrastable cavities.

[0005] According to a first aspect of the present invention, a method for ultrastable cavity-locked wide-range tuning with an anti-phase double-band is provided, the method comprising... Including the following steps: Acquire the target laser beam emitted by the target laser; After the target laser beam is input into the first modulator, the first intermediate laser beam is obtained; After the first intermediate laser beam is input to the second modulator, the second intermediate laser beam is obtained, wherein the second modulator is driven by a driving circuit to generate a double-sideband laser signal; After the second intermediate laser beam is input into the PDH optical path, the key laser beam is obtained; After the key laser beam is input into the target FP cavity, the output light of the target FP cavity is detected, and a feedback signal is generated to the target laser to lock the frequency of the output light onto the target FP cavity.

[0006] Specifically, the first modulator is an acousto-optic modulator.

[0007] Specifically, the second modulator is an electro-optic modulator.

[0008] Specifically, the driving circuit includes: a signal processing module, a first bias module, a second bias module, and an IQ modulator, wherein, The signal processing module is configured to receive a first baseband signal and convert it into a first differential signal pair; The first bias module is configured to apply a first DC bias condition to the first differential signal pair; The second bias module is configured to provide a second DC bias signal; The IQ modulator has a first modulation channel and a second modulation channel, wherein the input of the first modulation channel is connected to receive the first differential signal pair from the first signal processing module and biased by the first DC bias condition; the input of the second modulation channel is connected to receive the second DC bias signal from the second bias module; the first DC bias condition and the second DC bias signal are configured to work together such that the IQ modulator outputs a carrier and a double-sideband signal to drive the second modulator.

[0009] Specifically, the first signal processing module includes a single-ended to differential amplifier.

[0010] Specifically, the second bias module includes a single-ended to differential amplifier.

[0011] Specifically, the step of inputting the key laser beam into the target FP cavity, detecting the output light of the target FP cavity, and generating a feedback signal to the target laser to lock the frequency of the output light onto the target FP cavity further includes: After the key laser beam is input into the target FP cavity, the final laser beam is obtained; The frequency of the final laser beam is acquired and matched with a preset frequency; When the difference between the frequency of the final laser beam and the preset frequency is greater than the preset frequency difference threshold, a first error is generated; The error signal is fed back to the target laser and the acousto-optic modulator to control the target laser to adjust the driving frequency of the piezoelectric ceramic of the target laser and the acousto-optic modulator so that the frequency of the final laser beam is locked on the target FP cavity.

[0012] Specifically, the above-described method is applied to an ultra-stable cavity-locked wide-tuning device, which includes: a target laser 1, a first modulator 2, a second modulator 3, a PDH optical path 4, a target FP cavity 5, a driving circuit 6, and a detector; The target laser 1 is used to emit the target laser beam; The first modulator 2 is used to generate a first intermediate laser beam after receiving the target laser beam; The second modulator 3 is used to generate a second intermediate laser beam after receiving the first intermediate laser beam, wherein the second modulator 2 is driven by the driving circuit 6 to generate a double-sideband anti-phase laser signal; The PDH optical path 4 is used to receive the second intermediate laser beam, generate a key laser beam, and input the key laser beam into the target FP cavity 5; The detector is configured to detect the output light of the target FP cavity 5 and generate a feedback signal to the target laser 1 to lock the frequency of the output light onto the target FP cavity 5.

[0013] Specifically, the IQ modulator generates a frequency-tunable radio frequency microwave signal f2, which is mapped onto the optical frequency by an electro-optic modulator, resulting in a frequency shift of -f2 and +f2 in the optical frequency. The light shifted by -f2 or +f2 is locked to the target FP cavity to change the laser frequency by adjusting f1.

[0014] Specifically, the process also includes the following steps to obtain m1 and m2 in the IQ modulator: Obtain the sample cavity frequency error information D, where D = {D1, D2, ..., D} j , ..., D z}, D j It is the frequency error information of the j-th sample cavity, where the value of j ranges from 1 to z, and z is the number of sample cavity frequency error information. Based on D, obtain the sample modulation parameters M = {M1, M2, ..., M} corresponding to D. j M z}, Mj =(M j1 M j2 ), where M j1 It is D j The corresponding modulation parameters of the I-path, M j2 It is D j The corresponding modulation parameters for the Q-path; Obtain the modulation parameter M of the maximum I path from W. 1 max and the modulation parameters M of the minimum I-path 1 min ; Obtain the modulation parameter M of the maximum Q path from W. 2 max The modulation parameters M of the minimum Q path 2 min ; According to M 1 max M 1 min M 2 max and M 2 min We obtain m1 and m2.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention acquires a target laser beam emitted by a target laser; after inputting the target laser beam to a first modulator, a first intermediate laser beam is acquired; after inputting the first intermediate laser beam to a second modulator, a second intermediate laser beam is acquired, wherein the second modulator is driven by a driving circuit to generate a double-sideband laser signal; after inputting the second intermediate laser beam to a PDH optical path, a key laser beam is acquired; after inputting the key laser beam to a target FP cavity, the output light of the target FP cavity is detected, and a feedback signal is generated to the target laser to lock the frequency of the output light onto the target FP cavity; it can be seen that, compared with the prior art of tuning the ultra-stable reference itself and using sideband locking technology to make the target laser act as a "slave device" to track this moving reference in real time, while maintaining high stability, a wide range of tuning can also be achieved, solving the contradiction between stability and wide tuning. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of an ultrastable cavity-locked wide-range tuning method with an inverted double-sideband design provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of an ultra-stable cavity-locked wide-range tuning device provided in Embodiment 2 of the present invention; Among them, 1-target laser, 2-first modulator, 3-second modulator, 4-first PDH optical path, 5-target FP cavity, and 6-IQ modulator. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0019] This embodiment provides an ultrastable cavity-locked wide-range tuning method for an inverted double-band inverted double-band system. The method includes the following steps: Figure 1 As shown: Acquire the target laser beam emitted by the target laser; After the target laser beam is input into the first modulator, the first intermediate laser beam is obtained; After the first intermediate laser beam is input to the second modulator, the second intermediate laser beam is obtained, wherein the second modulator is driven by a driving circuit to generate a double-sideband laser signal; After the second intermediate laser beam is input into the PDH optical path, the key laser beam is obtained; After the key laser beam is input into the target FP cavity, the output light of the target FP cavity is detected, and a feedback signal is generated to the target laser to lock the frequency of the output light onto the target FP cavity.

[0020] Furthermore, the first modulator is an acousto-optic modulator.

[0021] Furthermore, the second modulator is an electro-optic modulator.

[0022] Furthermore, the driving circuit includes: a signal processing module, a first bias module, a second bias module, and an IQ modulator, wherein, The signal processing module is configured to receive a first baseband signal and convert it into a first differential signal pair.

[0023] In some embodiments, the first signal processing module includes a single-ended to differential amplifier.

[0024] In some implementations, the first baseband signal is a pre-set signal that the user can determine according to their needs. For example, a pure sine wave of 10 MHz, 500 mVpp, and 0 Vdc can be used as the first baseband signal and input into the signal processing module to convert it into a first differential signal pair.

[0025] The first bias module is configured to apply a first DC bias condition to the first differential signal pair. For example, a bias of 0.5Vdc is applied to one of the differential signals in the first differential signal pair; this bias is the first DC bias condition. This bias creates conditions for the subsequent generation of double-sideband in the IQ modulator.

[0026] The second bias module is configured to provide a second DC bias signal.

[0027] In some embodiments, the second bias module includes a single-ended to differential amplifier.

[0028] The second bias module applies a DC bias to each of its two outputs, which are then input to the two input ports of the IQ modulator. These two DC biases create a fixed phase difference within the IQ modulator. The second bias module applies a 0.3V DC bias to one output and a 0.7V DC bias to the other. The difference between 0.3V and 0.7V (0.4V) causes a fixed 90-degree (π / 2) phase shift in the Q-path of the IQ modulator relative to the I-path. This step is also one of the key conditions for generating double-sideband modulation.

[0029] The IQ modulator has a first modulation channel and a second modulation channel, wherein the input of the first modulation channel is connected to receive a first differential signal pair from the first signal processing module and biased by the first DC bias condition; the input of the second modulation channel is connected to receive a second DC bias signal from the second bias module; the first DC bias condition and the second DC bias signal are configured to work together such that the IQ modulator outputs a carrier and a double-sideband signal with one sideband suppressed to drive the second modulator.

[0030] Under these specific bias and drive conditions, the RF output of the IQ modulator will be a double-sideband signal with the carrier suppressed. Specifically, it will produce a double-sideband signal of +10MHz (or -10MHz, depending on the sign of the phase shift, which depends on the first baseband signal).

[0031] Under the double-sideband modulation of the aforementioned driving circuit, the radio frequency signal used to drive the second modulator includes a single-sideband frequency component in addition to the main frequency, thus ensuring that the laser component output by the second modulator consists only of double-sideband frequency components besides the main carrier frequency. The advantage is that it avoids signal confusion and crosstalk, and also makes the PDH error signal clearer and more stable, thereby enabling more precise and robust laser frequency locking.

[0032] Specifically, the step of inputting the key laser beam into the target FP cavity, detecting the output light of the target FP cavity, and generating a feedback signal to the target laser to lock the frequency of the output light onto the target FP cavity further includes the following steps: After the key laser beam is input into the target FP cavity, the final laser beam is obtained; The frequency of the final laser beam is acquired and matched with a preset frequency; An error signal is generated when the difference between the frequency of the final laser beam and the preset frequency is greater than the preset frequency difference threshold. The error signal is fed back to the target laser to control the target laser to adjust the piezoelectric ceramic of the target laser so that the frequency of the final laser beam is locked on the target FP cavity.

[0033] In a specific embodiment, such as Figure 2 As shown, the method is applied to an ultra-stable cavity locked wide-tuning device, which includes: a target laser 1, a first modulator 2, a second modulator 3, a PDH optical path 4, a target FP cavity 5, a driving circuit 6, and a detector. The target laser 1 is used to emit a target laser beam; The first modulator 2 is used to generate a first intermediate laser beam after receiving the target laser beam; The second modulator 3 is used to generate a second intermediate laser beam after receiving the first intermediate laser beam, wherein the second modulator 2 is driven by the driving circuit 6 to generate a double-sideband laser signal; The PDH optical path 4 is used to receive the second intermediate laser beam, generate a key laser beam, and input the key laser beam into the target FP cavity 5; The detector is configured to detect the output light of the target FP cavity 5 and generate a feedback signal to the target laser 1 to lock the frequency of the output light onto the target FP cavity 5.

[0034] In the above embodiment, the first modulator, driven by the frequency source f1, shifts the laser frequency from the original frequency f0 to f0+f1 to get as close as possible to the resonant frequency point of the target FP cavity.

[0035] The second modulator is driven by frequency source f2. This second modulator is a phase modulator that generates a series of sidebands on both sides of the laser carrier when a driving RF signal is applied. Frequency source f2 originates from the double-sideband signal output from driving circuit 6. Driven by this signal, the optical field output by the second modulator comprises the main carrier and a single optical sideband, where the main carrier frequency = f0 + f1, where f1 originates from AOM1, and the single optical sideband frequency = main carrier frequency + f2.

[0036] The role of the PDH optical path is to direct a portion of the laser (including the carrier and sideband) into the target FP cavity. Since the FP cavity has extremely high transmittance only for light of a specific resonant frequency, PDH technology generates an error signal by detecting the light reflected from the FP cavity. The zero point of this error signal corresponds to the laser frequency being exactly equal to the resonant frequency of the FP cavity. This error signal is fed back to the laser's PZT (Precision Z-T). The PZT can finely adjust the laser's cavity length, thereby changing its output frequency. The feedback loop continuously adjusts the PZT to ensure the error signal remains zero, thus locking the main carrier frequency to the resonant frequency of the target FP cavity.

[0037] Since the sidebands are derived from the carrier through a fixed electrical process, their relative frequency relationships are extremely stable and precise. The frequency stability of the sidebands completely inherits the stability of the main carrier, while their frequencies can be continuously adjusted relative to the main carrier over a wide range. Based on the above method, continuous and precise frequency tuning from hundreds of MHz to several GHz can be achieved. This solves the problem of insufficient AOM bandwidth. It avoids the problems of complex optical alignment, high insertion loss, and large system size caused by using multiple AOMs or broadband AOMs. All precise frequency generation is completed in the electrical domain and in a single EOM, making it easier to integrate and control. It combines the ultra-high frequency stability of FP cavities (achieved through carrier locking) with the wide-range tunability of electrical double-sidebands.

[0038] In some embodiments, the driving circuit 6 includes: a signal processing module 61, a first bias module 62, a second bias module 63, and an IQ modulator 64, wherein... The signal processing module 61 is configured to receive a first baseband signal and convert it into a first differential signal pair.

[0039] The first bias module 62 is configured to apply a first DC bias condition to the first differential signal pair.

[0040] The second bias module 63 is configured to provide a second DC bias signal.

[0041] The IQ modulator 64 has a first modulation channel and a second modulation channel, wherein the input of the first modulation channel is connected to receive the first differential signal pair from the first signal processing module and biased by the first DC bias condition; the input of the second modulation channel is connected to receive the second DC bias signal from the second bias module; the first DC bias condition and the second DC bias signal are configured to work together such that the IQ modulator outputs a carrier and a double-sideband signal with one sideband suppressed to drive the second modulator.

[0042] The IQ modulator generates a frequency-tunable radio frequency microwave signal f2, which is mapped onto an optical frequency by an electro-optic modulator, resulting in a frequency shift of -f2 and +f2 in the optical frequency. The light shifted by -f2 or +f2 is locked onto the target FP cavity to change the laser frequency by adjusting f2.

[0043] In some implementations, the signal processing module 61 can be an AD8138 single-ended to differential module.

[0044] In some implementations, the second bias module 63 can also be an AD8138 single-ended to differential module.

[0045] In some implementations, the IQ modulator 64 can be an ADRF6755 IQ modulator.

[0046] In one specific implementation, the IQ modulator 6 receives a radio frequency signal source with a frequency of f1 in channel I to obtain a first error signal.

[0047] In one specific implementation, the Q channel of the IQ modulator 6 receives a radio frequency signal source with a frequency of f2 and obtains a second error signal.

[0048] In one specific implementation, the IQ modulator 6 generates an optical field E out E out The following conditions must be met: .

[0049] Furthermore, the process also includes the following steps to obtain m1 and m2 in the IQ modulator: Obtain the sample cavity frequency error information D, where D = {D1, D2, ..., D} j , ..., D z}, D j It is the frequency error information of the j-th sample cavity, where the value of j ranges from 1 to z, and z is the number of sample cavity frequency error information. Based on D, obtain the sample modulation parameters M = {M1, M2, ..., M} corresponding to D. j Mz}, M j =(M j1 M j2 ), where M j1 It is D j The corresponding modulation parameters of the I-path, M j2 It is D j The corresponding modulation parameters for the Q-path; Obtain the modulation parameter M of the maximum I path from W. 1 max and the modulation parameters M of the minimum I-path 1 min ; Obtain the modulation parameter M of the maximum Q path from W. 2 max The modulation parameters M of the minimum Q path 2 min ; According to M 1 max M 1 min M 2 max and M 2 min We obtain m1 and m2.

[0050] Furthermore, according to M 1 max M 1 min M 2 max and M 2 min The steps to obtain m1 and m2 also include the following: According to M 1 max M 1 min M 2 max and M 2 min Obtain the length and width of the initial modulation parameter region, where the length ΔM1 and width ΔM2 of the initial modulation parameter region are given, and ΔM1 satisfies the following condition: ΔM1 = M 1 max -M 1 min △M2 satisfies the following condition: △M2=M 2 max -M 2 min .

[0051] Based on ΔM1 and ΔM2, the region is divided into sub-modulation parameter regions C = {C1, C2, ..., C...} t , ..., C g}, C t It is the t-th sub-modulation parameter region, where t ranges from 1 to g, and g is the number of sub-modulation parameter regions, with g being greater than 1.

[0052] Furthermore, the size information of each of the sub-modulation parameter regions is consistent; wherein the length 'a' of the sub-frequency variation weight region and the width 'b' of the sub-modulation parameter region, wherein 'a' satisfies the following condition: M q1 It is M 11 To M j1 The modulation parameter of the q-th I-channel, where q ranges from 1 to j.

[0053] Among them, b meets the following conditions: .

[0054] Based on M and C, determine the number of adjustment parameters H corresponding to C: H = {H1, H2, ..., H} t H g}, H t It is C t This corresponds to the number of adjustment parameters.

[0055] Furthermore, based on M and C, determine the number of adjustment parameters H = {H1, H2, ..., H} corresponding to C. t H g}, H t It is C t The steps for adjusting the number of parameters also include the following: M j With any C t Perform a match; When M j Located in C t Inside, H t The number of adjusted parameters counted is increased by 1; When M j Not in C t Inside, H t The number of adjustment parameters counted remains unchanged.

[0056] Iterate through H and if H t When the maximum number of adjustment parameters in H is determined, H is determined. t The center point (M) t and Y t ), to make X t As m1 and Y t As m2.

[0057] In summary, the process involves: acquiring the target laser beam emitted by the target laser; inputting the target laser beam into a first modulator to acquire a first intermediate laser beam; inputting the first intermediate laser beam into a second modulator to acquire a second intermediate laser beam, wherein the second modulator is driven by a driving circuit to generate a double-sideband laser signal; inputting the second intermediate laser beam into a PDH optical path to acquire a key laser beam; inputting the key laser beam into the target FP cavity to detect the output light of the target FP cavity and generating a feedback signal to the target laser to lock the frequency of the output light onto the target FP cavity. It can be seen that, compared to the prior art which uses tuning of the ultra-stable reference itself and employs sideband locking technology to make the target laser act as a "slave device" to track this moving reference in real time, this method maintains high stability while achieving a wide tuning range, thus resolving the contradiction between stability and wide tuning range.

[0058] While specific embodiments of the invention have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. It should also be understood that various modifications can be made to the embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for ultrastable cavity locking with wide tuning over an anti-phase double-band, characterized in that, The method includes: Acquire the target laser beam emitted by the target laser; After the target laser beam is input into the first modulator, the first intermediate laser beam is obtained; After the first intermediate laser beam is input to the second modulator, the second intermediate laser beam is obtained. The second modulator is driven by a driving circuit to generate a double-sideband laser signal. The driving circuit includes a signal processing module, a first bias module, a second bias module, and an IQ modulator. The signal processing module is configured to receive a first baseband signal and convert it into a first differential signal pair. The first bias module is configured to apply a first DC bias condition to the first differential signal pair; The second bias module is configured to provide a second DC bias signal; The IQ modulator has a first modulation channel and a second modulation channel, wherein the input terminal of the first modulation channel is connected to receive a first differential signal pair from the first signal processing module and biased by the first DC bias condition; the input terminal of the second modulation channel is connected to receive a second DC bias signal from the second bias module; the first DC bias condition and the second DC bias signal are configured to co-drive the second modulator by the IQ modulator outputting a carrier and a double-sideband signal, and the IQ modulator outputting an inverse double-sideband signal with the carrier suppressed and the upper and lower sidebands having opposite phases to drive the second modulator. After the second intermediate laser beam is input into the PDH optical path, the key laser beam is obtained; After the key laser beam is input into the target FP cavity, the output light of the target FP cavity is detected, and a feedback signal is generated to the target laser to lock the frequency of the output light onto the target FP cavity.

2. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The first modulator is an acousto-optic modulator.

3. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The second modulator is an electro-optic modulator.

4. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The first signal processing module includes a single-ended to differential amplifier.

5. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The second bias module includes a single-ended to differential amplifier.

6. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The step of inputting the key laser beam into the target FP cavity, detecting the output light of the target FP cavity, and generating a feedback signal to the target laser to lock the frequency of the output light onto the target FP cavity further includes: After the key laser beam is input into the target FP cavity, the final laser beam is obtained; The frequency of the final laser beam is acquired and matched with a preset frequency; When the difference between the frequency of the final laser beam and the preset frequency is greater than the preset frequency difference threshold, a first error is generated; The error signal is fed back to the target laser and the acousto-optic modulator to control the target laser to adjust the driving frequency of the piezoelectric ceramic of the target laser and the acousto-optic modulator so that the frequency of the final laser beam is locked on the target FP cavity.

7. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, wherein the method is applied to an ultrastable cavity-locked wide-range tuning device, characterized in that, The device includes: a target laser 1, a first modulator 2, a second modulator 3, a PDH optical path 4, a target FP cavity 5, a driving circuit 6, and a detector; The target laser 1 is used to emit the target laser beam; The first modulator 2 is used to generate a first intermediate laser beam after receiving the target laser beam; The second modulator 3 is used to generate a second intermediate laser beam after receiving the first intermediate laser beam, wherein the second modulator 2 is driven by the driving circuit 6 to generate a double-sideband anti-phase laser signal; The PDH optical path 4 is used to receive the second intermediate laser beam, generate a key laser beam, and input the key laser beam into the target FP cavity 5; The detector is configured to detect the output light of the target FP cavity 5 and generate a feedback signal to the target laser 1 to lock the frequency of the output light onto the target FP cavity 5.

8. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The IQ modulator generates a frequency-tunable radio frequency microwave signal f2, which is mapped onto an optical frequency by an electro-optic modulator, resulting in a frequency shift of -f2 and +f2 in the optical frequency. The light shifted by -f2 or +f2 is locked onto the target FP cavity to change the laser frequency by adjusting f1.

9. The ultrastable cavity-locked wide-range tuning method with anti-phase double-band according to claim 1, characterized in that, The process also includes obtaining m1 and m2 in the IQ modulator using the following steps: Obtain the sample cavity frequency error information D, where D = {D1, D2, ..., D} j , ..., D z }, D j It is the frequency error information of the j-th sample cavity, where the value of j ranges from 1 to z, and z is the number of sample cavity frequency error information. Based on D, obtain the sample modulation parameters M = {M1, M2, ..., M} corresponding to D. j M z }, M j =(M j1 M j2 ), where M j1 It is D j The corresponding modulation parameters of the I-path, M j2 It is D j The corresponding modulation parameters for the Q-path; Obtain the modulation parameter M of the maximum I path from W. 1 max and the modulation parameters M of the minimum I-path 1 min ; Obtain the modulation parameters M of the maximum Q path from W. 2 max The modulation parameters M of the minimum Q path 2 min ; According to M 1 max M 1 min M 2 max and M 2 min We obtain m1 and m2.

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