A microcavity dual optical comb frequency stabilization device based on CPT effect

Abstract

The application discloses a kind of based on CPT effect microcavity double optical comb frequency stabilization device, two self-injection locking microcavity optical comb are used to obtain microcavity double optical comb, and microcavity double optical comb pump light source is locked;The repetition frequency of double optical comb is independently controlled by the way of radio frequency injection locking;Utilize microcavity double optical comb vernier effect, obtain the double optical comb comb teeth pair that can stimulate CPT effect, utilize atomic absorption peak to generate comb teeth frequency discrimination signal, feedback to pump light, so that pump light reference to the Doppler absorption peak of atom;The repetition frequency of one optical comb is referenced to comb teeth beat signal, and frequency discrimination signal is generated using CPT effect, and the repetition frequency of another optical comb is locked, so that the frequency difference of double optical comb comb teeth pair is locked to CPT resonance peak.The application can compensate the frequency difference between microcavity optical comb repetition frequency and microwave atomic frequency stabilization frequency by double optical comb vernier effect, realize the integration and miniaturization of frequency stabilization system, reduce the complexity of frequency stabilization system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microcavity optical comb frequency stabilization and wavelength standard, and particularly relates to a microcavity double optical comb frequency stabilization device based on CPT (Coherent Population Trapping) effect. BACKGROUND

[0002] Optical frequency comb is periodic pulse in time domain and equally spaced comb teeth in frequency domain. The soliton pulse excited by microcavity is called microcavity optical comb. The traditional optical frequency comb frequency stabilization method needs to stabilize the offset frequency and repetition frequency of the optical comb. Since the microcavity has a small size, the repetition frequency of the microcavity optical comb generated thereby is mostly between 10 GHz and 200 GHz. In particular, the repetition frequency of the microcavity optical comb based on integrated photon technology is difficult to be lower than 20 GHz, which has a large gap from the frequency corresponding to the existing microwave atomic frequency stabilization technology (6.83 GHz corresponds to rubidium atom, 9.19 GHz corresponds to cesium atom, 1.42 GHz corresponds to hydrogen atom, etc.), which is not conducive to the integration and miniaturization of the microcavity optical comb and the atomic frequency stabilization system thereof, and cannot exert the potential advantage of on-chip integration of the microcavity optical comb. The high repetition frequency of the current microcavity optical comb makes it difficult to directly detect and use the atomic stabilized repetition frequency, which has high cost and system complexity. SUMMARY

[0003] The purpose of the present application is to provide a microcavity double optical comb frequency stabilization device based on CPT effect, which can compensate for the frequency difference between the repetition frequency of the microcavity optical comb and the microwave atomic frequency stabilization frequency through the double optical comb vernier effect, realize the direct combination and on-chip integration of the microcavity optical comb and the microwave atomic frequency stabilization system, thereby realizing the integration and miniaturization of the frequency stabilization system and reducing the complexity of the frequency stabilization system.

[0004] In order to achieve the above-mentioned purpose, one aspect of the present application provides a microcavity double optical comb frequency stabilization device based on CPT effect, comprising first and second microcavity optical comb modules, first and second microwave sources, first to third photodetectors, first to fourth frequency locking circuits, an adjustable optical filter and an Rb atomic cell.

[0005] The first microcavity optical comb module comprises a first DFB laser, and the second microcavity optical comb module comprises a second DFB laser. The first microcavity optical comb module is used to excite a first self-injection-locked microcavity optical comb as a master comb, and the second microcavity optical comb module is used to excite a second self-injection-locked microcavity optical comb as a slave comb. The master comb realizes injection locking of the repetition frequency through a microwave signal from the first microwave source, and the slave comb realizes injection locking of the repetition frequency through a microwave signal from the second microwave source.

[0006] The pump light comb teeth of the master comb and the pump light comb teeth of the slave comb pass through a third photoelectric detector to beat an output radio frequency signal, and pass through a fourth frequency locking circuit to be fed back to the second DFB laser to lock the radio frequency signal, so that the wavelength of the second DFB laser output follows the wavelength of the first DFB laser output;

[0007] The master comb and the slave comb pass through an adjustable optical filter to filter out a pair of comb teeth, which are split into a first comb tooth pair and a second comb tooth pair, the first comb tooth pair passes through a first photoelectric detector to beat an output radio frequency signal, and passes through a third frequency locking circuit to be fed back to the second microwave source to lock the radio frequency signal;

[0008] The second comb tooth pair is incident on the Rb atomic cell as coherent double-color light, the Doppler absorption spectrum signal and the CPT resonance signal of the Rb atom are obtained through a second photoelectric detector, the Doppler absorption signal is fed back to the first DFB laser through a first frequency locking circuit to lock the output wavelengths of the first DFB laser and the second DFB laser on the Doppler absorption peak of the Rb atomic ground state energy level transition, and the CPT resonance signal is fed back to the first microwave source through a second frequency locking circuit, and the frequency difference of the second comb tooth pair is locked on the frequency difference of the Rb atomic ground state hyperfine energy level by using the frequency discrimination signal of the CPT effect.

[0009] According to the above aspect of the application, the microcavity double optical comb frequency stabilization device based on the CPT effect can compensate for the frequency difference between the microcavity optical comb repetition frequency and the microwave atomic frequency stabilization frequency through the double optical comb vernier effect, realize the direct combination and on-chip integration of the microcavity optical comb and the microwave atomic frequency stabilization system, and thus realize the integration and miniaturization of the frequency stabilization system and reduce the complexity of the frequency stabilization system. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings used in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor:

[0011] Figure 1 is a system block diagram of a microcavity double optical comb frequency stabilization device based on the CPT effect according to an embodiment of the present application. DETAILED DESCRIPTION

[0012] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0013] One embodiment of the present application provides a microcavity dual optical comb frequency stabilization device based on CPT effect, as shown in the figure. Figure 1 The microcavity dual optical comb frequency stabilization device of the embodiment of the present application includes a first microcavity optical comb module 1, a second microcavity optical comb module 2, an adjustable optical filter 3, a first photodetector 4, an optical lens group 5, an Rb atomic physics system 6, a second photodetector 7, a first frequency locking circuit 8, a second frequency locking circuit 9, a third frequency locking circuit 10, a third photodetector 11, a fourth frequency locking circuit 12, a first microwave source 13, and a second microwave source 14.

[0014] The first microcavity optical comb module 1 and the second microcavity optical comb module 2 have the same structure, the first microcavity optical comb module 1 includes a first DFB laser 1-1, a first microcavity chip 1-2, and a first waveguide chip 1-3, the first microcavity chip 1-2 includes a first micro-ring 1-4, a first waveguide 1-5, a second waveguide 1-6, a first heater 1-7, a second heater 1-8, and a third heater 1-9, and the first waveguide chip 1-3 includes a first waveguide beam splitter 1-10, a second waveguide beam splitter 1-11, a first adjustable optical waveguide filter 1-12, and a first on-chip microwave modulator 1-13.

[0015] The second microcavity optical comb module 2 includes a second DFB laser 2-1, a second microcavity chip 2-2, and a second waveguide chip 2-3, the second microcavity chip 2-2 includes a second micro-ring 2-4, a third waveguide 2-5, a fourth waveguide 2-6, a fourth heater 2-7, a fifth heater 2-8, and a sixth heater 2-9, and the second waveguide chip 2-3 includes a third waveguide beam splitter 2-10, a fourth waveguide beam splitter 2-11, a second adjustable optical waveguide filter 2-12, and a second on-chip microwave modulator 2-13.

[0016] The Rb atomic physics system 6 includes an Rb atomic cell, a cell magnetic-free heater, a weak magnetic coil, and a magnetic shielding cover. The optical lens group 5 is arranged between the adjustable optical filter 3 and the Rb atomic physics system 6, and includes a frequency doubling crystal, a 1 / 2 wave plate, a polarizer, and a 1 / 4 wave plate, for frequency doubling of coherent dual-color light incident on the Rb atomic cell and adjusting the power and circular polarization thereof.

[0017] In the first microcavity optical comb module 1, the pump light is emitted from the first DFB laser 1-1, directly coupled with the first micro-ring 1-4 through the first waveguide 1-5, the current of the first DFB laser 1-1 is adjusted and the phase of the pump light is adjusted through the first heater 1-7, so that it is in the self-injection locking comb excitation state, and the excited comb is recorded as the main comb. The main comb is divided into the first main comb and the second main comb through the first waveguide beam splitter 1-10, wherein the first main comb is coupled out of the first microcavity optical comb module 1 through the optical fiber, and the second main comb is filtered through the first adjustable optical waveguide filter 1-12 to obtain the pump light corresponding to the comb tooth wavelength, recorded as the main comb pump light, and then passed through the second waveguide beam splitter 1-11 to be divided into the first pump light of the main comb and the second pump light of the main comb, the first pump light of the main comb is coupled out of the first microcavity optical comb module 1 through the optical fiber, and the second pump light of the main comb is passed through the first on-chip microwave modulator 1-13 and coupled with the first micro-ring 1-4 through the second waveguide 1-6, the third heater 1-9 adjusts the phase of the second pump light of the main comb to be the same as the in-cavity light field phase of the first micro-ring 1-4, at this time, the external microwave can be injected into the first micro-ring 1-4 through the first on-chip microwave modulator 1-13, so as to realize the injection locking of the repetition frequency of the microcavity optical comb.

[0018] In the second microcavity optical comb module 2, the pump light is emitted from the second DFB laser 2-1, directly coupled with the second micro-ring 2-4 through the third waveguide 2-5, the current of the second DFB laser 2-1 is adjusted and the phase of the pump light is adjusted through the fourth heater 2-7, so that it is in the self-injection locking comb excitation state, and the excited comb is recorded as the slave comb. The slave comb is divided into the first slave comb and the second slave comb through the third waveguide beam splitter 2-10, wherein the first slave comb is coupled out of the second microcavity optical comb module 2 through the optical fiber, and the second slave comb is filtered through the second adjustable optical waveguide filter 2-12 to obtain the pump light corresponding to the comb tooth wavelength, recorded as the slave comb pump light, and then passed through the fourth waveguide beam splitter 2-11 to be divided into the first pump light of the slave comb and the second pump light of the slave comb, the first pump light of the slave comb is coupled out of the second microcavity optical comb module 2 through the optical fiber, and the second pump light of the slave comb is passed through the second on-chip microwave modulator 2-13 and coupled with the second micro-ring 2-4 through the fourth waveguide 2-6, the sixth heater 2-9 adjusts the phase of the second pump light of the slave comb to be the same as the in-cavity light field phase of the second micro-ring, at this time, the external microwave can be injected into the second micro-ring through the second on-chip microwave modulator 2-13, so as to realize the injection locking of the repetition frequency of the microcavity optical comb.

[0019] The first pump light of the main comb and the first pump light of the slave comb output through the optical fiber are frequency-mixed by the third photodetector 11 to output a radio frequency signal, and the radio frequency signal is fed back to the current input end of the second DFB laser 2-1 through the fourth frequency locking circuit 12 to lock the radio frequency signal, so as to realize the wavelength following of the second DFB laser 2-1 to the wavelength of the first DFB laser 1-1.

[0020] The first master comb and the first slave comb outputted by the optical fiber outside the chip pass through the adjustable optical filter 3 to filter out a pair of combs, and are split into a first comb pair and a second comb pair. The first comb pair after splitting passes through the first photodetector 4 to output a radio frequency signal, and is fed back to the second microwave source 14 through the third frequency locking circuit 10 to realize the locking of the output radio frequency signal.

[0021] The second comb pair, as coherent double-color light, is multiplied by five through the optical lens group 5 and adjusted in power and circular polarization, and then is incident on the Rb atomic physical system 6. The Doppler absorption spectrum signal and the coherent population trapping (CPT) resonance signal of the Rb atomic physical system are obtained through the second photodetector 7. The Doppler absorption signal is fed back to the current input end of the first DFB laser 1-1 through the first frequency locking circuit 8, so as to lock the output wavelengths of the first DFB laser 1-1 and the second DFB laser 2-1 to the Doppler absorption peak of the Rb atomic ground state energy level transition. The CPT resonance signal is fed back to the first microwave source 13 through the second frequency locking circuit 9, and the frequency difference of the second comb pair is locked to the frequency difference of the Rb atomic ground state hyperfine energy level by using the frequency discrimination signal of the coherent population trapping effect.

[0022] The first microcavity optical comb module 1 and the second microcavity optical comb module 2 adopt InP laser chips, silicon nitride microcavity chips, and lithium niobate waveguide chips. The coupling between the chips adopts end-to-end direct coupling without using microlenses. The chips are integrated in a package by packaging integration or hetero-integration, so that the entire frequency stabilization device has the basis of miniaturization and integration. The first microcavity chip 1-2 and the second microcavity chip 2-2 correspond to silicon nitride microcavity chips. The first micro-ring 1-4 and the second micro-ring 2-4 have different free spectral ranges, and the difference between the free spectral ranges is between 100 MHz and 1 GHz. In addition, the first micro-ring 1-4 and the second micro-ring 2-4 have a neighboring (differing by tens of MHz) resonance peak near 1550 nm, which can be adjusted by the second heater 1-8 and the fifth heater 2-8, respectively. The quality factor of the first micro-ring 1-4 and the second micro-ring 2-4 is above 5E6. The first waveguide chip 1-3 and the second waveguide chip 2-3 adopt lithium niobate waveguide chips.

[0023] In order to reduce the loss of mode crosstalk noise and additional noise, the waveguides used on the first microcavity chip 1-2, the second microcavity chip 2-2, the first waveguide chip 1-3 and the second waveguide chip 2-3 are all single-mode waveguides. For the first DFB laser 1-1 and the second DFB laser 2-1, InP laser chips are used, and the output wavelength is near 1550 nm, which can be aligned with the resonance peaks of the first micro-ring 1-4 and the second micro-ring 2-4. In order to make the filtered comb teeth be able to excite the CPT phenomenon of Rb atoms, the bandwidths of the tunable optical filter 3, the first tunable optical waveguide filter 1-12 and the second tunable optical waveguide filter 2-12 need to be designed, wherein the bandwidth of the tunable optical filter 3 is smaller than the free spectral range of the first micro-ring 1-4 and the second micro-ring 2-4, and the center wavelength of the filter is near 1590 nm. The bandwidth of the first tunable optical waveguide filter 1-12 is smaller than the free spectral range of the first micro-ring 1-4, and the bandwidth of the second tunable optical waveguide filter 2-12 is smaller than the free spectral range of the second micro-ring 2-4, and the corresponding center wavelengths of the two are near 1550 nm.

[0024] In order to realize the RF injection locking of the repetition frequency of the microcavity optical comb, the parameters of the first microwave source 13 and the second microwave source 14 need to meet the following design, the output microwave frequency of the first microwave source 13 is near the free spectral range value of the first micro-ring 1-4, and the output microwave frequency of the second microwave source 14 is near the free spectral range value of the second micro-ring 2-4. Therefore, the first on-chip microwave modulator 1-13 and the second on-chip microwave modulator 2-13 also need to be designed with specific parameters, the modulation bandwidth of the first on-chip microwave modulator 1-13 is greater than the free spectral range of the first micro-ring 1-4, and the modulation bandwidth of the second on-chip microwave modulator 2-13 is greater than the free spectral range of the second micro-ring 2-4.

[0025] In summary, the microcavity dual optical comb frequency stabilization device based on the CPT effect of the embodiment of the application adopts a first self-injection locking microcavity optical comb and a second self-injection locking microcavity optical comb to obtain a microcavity dual optical comb. First, the microcavity dual optical comb pump light source is locked, and then the repetition frequencies of the dual optical combs are independently controlled in the form of RF injection locking. Then, by using the microcavity dual optical comb vernier effect, a dual optical comb comb tooth pair capable of exciting the CPT effect is obtained, wherein the repetition frequency of the second self-injection locking microcavity optical comb is referenced to the beat signal of the comb tooth pair. The absorption spectrum of the comb tooth pair is frequency discriminated by using the atomic Doppler absorption peak, so as to lock the optical frequency corresponding to the comb tooth pair to the atomic ground state energy level transition spectrum. The frequency discrimination signal is generated by using the CPT effect, the repetition frequency of the first self-injection locking microcavity optical comb is locked, so as to lock the frequency difference of the dual optical comb comb tooth pair to the CPT resonance peak. The frequency of the comb tooth pair is frequency discriminated by using the atomic absorption peak, and is fed back to the pump laser current, so as to realize the locking of the pump light. Finally, the microcavity dual optical comb is stabilized.

[0026] The following describes working principles of a microcavity double optical comb frequency stabilization device based on a CPT effect according to an embodiment of the application.

[0027] According to characteristics of the optical frequency comb, the mth comb tooth corresponds to a frequency f m and the nth comb tooth corresponds to a frequency f n which can be expressed as

[0028] (1)

[0029] (2)

[0030] wherein f pump1 and f pump2 are offset frequencies of the optical comb 1 (master comb) and the optical comb 2 (slave comb) respectively, f rep1 and f rep2 are repetition frequencies of the optical comb 1 and the optical comb 2 respectively, and the repetition frequency of the microcavity optical comb is equal to the frequency of the external RF source (microwave source) due to RF injection locking, and thus f m and f n are equal to each other.

[0031] (3)

[0032] wherein f RF1 and f RF2 are frequencies of the external RF source (microwave source) of the optical comb 1 and the optical comb 2 respectively. f m - f n After frequency multiplication by 2, the beat frequency signal k RF2 is locked to f

[0033] (4)

[0034] According to the formulae (3) and (4), the relationship between the beat frequency signals f m - f n and f RF1 can be obtained.

[0035] (5) ​

[0036] So far, the f m - f n relationship between f RF1 and f RF2 is established, f m - f n The frequency can be discriminated by the CPT resonance signal, so as to be locked to the frequency difference of the atomic ground state hyperfine level. Through this process, the repetition frequency of the microcavity dual optical comb is stabilized. It is worth noting that in this frequency stabilization method, formula (4) and formula (5) are realized through an electrical link, so f RF2 The locking bandwidth of formula (4) is limited, and the establishment of formula (4) requires time, so the frequency relationship obtained from formula (5) is only the steady-state solution of the system. Its transient characteristics are different from the steady-state characteristics, and when the repetition frequency f RF1 jitters, according to the optical link represented by formula (1) and (3), the jitter will be amplified by m times and transmitted to the m root comb f m , and then directly transmitted to the beat frequency f m - f n of the comb pair. Therefore, the CPT resonance signal has m times response to the jitter of the repetition frequency. It can be reasonably deduced that the measurement sensitivity of the repetition frequency jitter can be greatly improved through the dual optical comb vernier effect.

[0037] Combined with the CPT principle, using f m and f n wavelengths, the Doppler absorption peak of the atomic energy level transition is obtained and locked on the absorption peak, and the absolute frequency of the comb can be stabilized. Thus, the dual optical comb of the microcavity is obtained, and the repetition frequency is stabilized.

[0038] In this frequency stabilization method, by designing the FSR of the dual-coupled micro-ring cavity, it can be easily realized that f m - f n is approximately equal to the interval of the atomic hyperfine level. And it can make the output frequency of the microcavity optical comb no longer limited to the vicinity of the repetition frequency. At the same time, the measurement sensitivity of the CPT frequency stabilization system to the repetition frequency f rep1 of the optical comb 1 is improved by mThe repetition frequency stability of the microcavity optical comb can be further improved.

[0039] In conclusion, the microcavity double optical comb frequency stabilization device based on the CPT effect of the embodiment of the application combines the advantages of the CPT effect atomic frequency stabilization and the microcavity optical comb technology, compensates for the frequency difference between the repetition frequency of the microcavity optical comb and the frequency of the microwave atomic frequency stabilization through the double optical comb vernier effect, and can realize the direct combination and on-chip integration of the microcavity optical comb and the microwave atomic frequency stabilization physical system. The CPT effect of the atom and the vernier effect of the microcavity optical comb are combined, so that the atomic CPT effect can frequency discriminate the microcavity double optical comb, a double optical comb system is realized by using two self-injection-locked microcavity optical combs, the double optical comb comb teeth pair capable of exciting the CPT effect is obtained through the vernier effect of the microcavity double optical comb, the comb tooth frequency discrimination signal is generated by using the atomic absorption peak, and the signal is fed back to the pump light, so that the pump light is referenced to the Doppler absorption peak of the atom, the repetition frequency of one of the optical combs is referenced to the comb tooth beat signal, the frequency discrimination signal is generated by using the CPT effect, the repetition frequency of the other optical comb is locked, and the frequency difference of the double optical comb comb teeth pair is locked to the CPT resonance peak.

[0040] The microcavity double optical comb frequency stabilization device based on the CPT effect of the embodiment of the application has the following technical effects: by introducing the double optical comb system and the CPT frequency stabilization system on the basis of the self-injection-locked microcavity optical comb, the complete on-chip integration of the optical system is supported, a compact and miniaturized microcavity double optical comb frequency stabilization system can be realized, and the system has the potential of miniaturization and chipization, has a wide application prospect in the fields of precision measurement, low phase noise microwave generation, atomic clock timing and the like; by using the characteristics of the vernier effect of the double optical comb, the frequency matching difficulty between the high repetition frequency microcavity optical comb and the CPT frequency stabilization system is reduced, and the frequency stabilization system is simplified; based on the double optical comb vernier system, by using the characteristics that the optical bandwidth is much higher than the electrical bandwidth, the sensitivity of the frequency discrimination signal can be improved by orders of magnitude, so that the frequency stability can be obviously improved compared with the traditional frequency stabilization method.

[0041] The above only describes certain exemplary embodiments of the application by way of illustration, and it is needless to say that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the application. Therefore, the above figures and description are illustrative in nature and should not be understood as limiting the scope of protection of the claims of the application.

Claims

1. A microcavity dual optical comb frequency stabilization device based on CPT effect, characterized in that, The first and second microcavity optical comb modules, the first and second microwave sources, the first to third photodetectors, the first to fourth frequency locking circuits, the adjustable optical filter and the Rb atomic cell are included. The first microcavity optical comb module includes a first DFB laser, and the second microcavity optical comb module includes a second DFB laser; the first microcavity optical comb module is used for exciting a first self-injection-locked microcavity optical comb as a master comb, and the second microcavity optical comb module is used for exciting a second self-injection-locked microcavity optical comb as a slave comb; the master comb is injection-locked in the repetition frequency by a microwave signal from the first microwave source, and the slave comb is injection-locked in the repetition frequency by a microwave signal from the second microwave source. Pump comb teeth of the master comb and pump comb teeth of the slave comb are frequency-mixed by the third photodetector to output a radio frequency signal, and the radio frequency signal is fed back to the second DFB laser by the fourth frequency locking circuit to lock the radio frequency signal, so that the wavelength of the second DFB laser follows the wavelength of the first DFB laser. The master comb and the slave comb pass through the adjustable optical filter to filter out a pair of comb teeth, which are split into a first comb tooth pair and a second comb tooth pair; the first comb tooth pair is frequency-mixed by the first photodetector to output a radio frequency signal, and the radio frequency signal is fed back to the second microwave source by the third frequency locking circuit to lock the radio frequency signal. The second comb tooth pair is incident on the Rb atomic cell as coherent double-color light, and a Doppler absorption spectrum signal and a CPT resonance signal of the Rb atom are obtained by the second photodetector; the Doppler absorption signal is fed back to the first DFB laser by the first frequency locking circuit to lock the wavelengths of the first DFB laser and the second DFB laser to the Doppler absorption peak of the Rb atom ground state energy level transition; and the CPT resonance signal is fed back to the first microwave source by the second frequency locking circuit to lock the frequency difference of the second comb tooth pair on the frequency difference of the Rb atom ground state hyperfine energy level by using the frequency discrimination signal of the CPT effect.

2. The apparatus of claim 1, wherein, The first microcavity optical comb module further includes a first microcavity chip and a first waveguide chip; the first microcavity chip includes a first micro-ring, a first waveguide and a second waveguide; and the first waveguide chip includes a first waveguide beam splitter, a second waveguide beam splitter, a first adjustable optical waveguide filter and a first on-chip microwave modulator. Pump light emitted from the first DFB laser is directly coupled with the first micro-ring through the first waveguide to excite a first self-injection-locked optical comb as a master comb; the master comb is split into a first master comb and a second master comb by the first waveguide beam splitter, wherein the first master comb is coupled out of the first microcavity optical comb module chip through an optical fiber, and the second master comb filters out a comb tooth wavelength corresponding to pump light by the first adjustable optical waveguide filter to serve as master comb pump light; the second master comb is split into a first master comb pump light and a second master comb pump light by the second waveguide beam splitter, wherein the first master comb pump light is coupled out of the first microcavity optical comb module chip through an optical fiber, and the second master comb pump light is coupled with the first micro-ring through the second waveguide by passing through the first on-chip microwave modulator; the phase of the second master comb pump light is the same as the phase of the intracavity light field of the first micro-ring; and a microwave from the first microwave source is injected into the first micro-ring through the first on-chip microwave modulator to injection-lock the repetition frequency of the master comb.

3. The apparatus of claim 2, wherein, The first microcavity chip further comprises a first heater, a second heater and a third heater, the first heater is used for adjusting the pump light phase of the first DFB laser, the second heater is used for adjusting the resonance peak of the first micro-ring, and the third heater is used for adjusting the second pump light phase of the main comb to be the same as the intracavity light field phase of the first micro-ring.

4. The apparatus of claim 3, wherein, The second microcavity optical comb module further comprises a second microcavity chip and a second waveguide chip, the second microcavity chip comprises a second micro-ring, a third waveguide and a fourth waveguide, and the second waveguide chip comprises a third waveguide beam splitter, a fourth waveguide beam splitter, a second adjustable optical waveguide filter and a second on-chip microwave modulator; The pump light emitted from the second DFB laser is directly coupled with the second micro-ring through the third waveguide to excite the second self-injection-locked optical comb as a slave comb, the slave comb is divided into a first slave comb and a second slave comb through the third waveguide beam splitter, wherein the first slave comb is emitted out of the second microcavity optical comb module through fiber coupling, and the second slave comb filters out the comb tooth wavelength corresponding to the pump light as slave comb pump light through the second adjustable optical waveguide filter, and then is divided into slave comb first pump light and slave comb second pump light through the fourth waveguide beam splitter, the slave comb first pump light is emitted out of the second microcavity optical comb module through fiber coupling, and the slave comb second pump light is coupled with the second micro-ring through the fourth waveguide after passing through the second on-chip microwave modulator, the phase of the slave comb second pump light is the same as the intracavity light field phase of the second micro-ring, and the microwave from the second microwave source is injected into the second micro-ring through the second on-chip microwave modulator to realize injection locking of the slave comb repetition frequency.

5. The apparatus of claim 4, wherein, The second microcavity chip further comprises a fourth heater, a fifth heater and a sixth heater, the fourth heater is used for adjusting the pump light phase of the second DFB laser, the fifth heater is used for adjusting the resonance peak of the second micro-ring, and the sixth heater is used for adjusting the second pump light phase of the slave comb to be the same as the intracavity light field phase of the second micro-ring.

6. The apparatus of claim 5, wherein, The bandwidth of the adjustable optical filter is smaller than the free spectral range of the first micro-ring and the second micro-ring, and the center wavelength is near 1590 nm; The bandwidth of the first adjustable optical waveguide filter is smaller than the free spectral range of the first micro-ring, the bandwidth of the second adjustable optical waveguide filter is smaller than the free spectral range of the second micro-ring, and the center wavelengths of the first and second adjustable optical waveguide filters are near 1550 nm.

7. The apparatus of claim 6, wherein, The output microwave frequency of the first microwave source is near the free spectral range value of the first micro-ring, and the output microwave frequency of the second microwave source is near the free spectral range value of the second micro-ring; The modulation bandwidth of the first on-chip microwave modulator is greater than the free spectral range of the first micro-ring, and the modulation bandwidth of the second on-chip microwave modulator is greater than the free spectral range of the second micro-ring.

8. The device of any one of claims 1-7, wherein, Further comprising an optical lens group arranged between the adjustable optical filter and the Rb atom cell, used for frequency doubling and adjusting the power and circular polarization of the incident coherent double-color light to the Rb atom cell.

9. The apparatus of any one of claims 4-7, wherein, The first micro-ring and the second micro-ring have different free spectral ranges, and the difference between the free spectral ranges is between 100 MHz and 1 GHz; the first micro-ring and the second micro-ring have an adjacent resonance peak near 1550 nm; The output wavelengths of the first DFB laser and the second DFB laser are near 1550 nm, and can be aligned with the resonance peaks of the first microcavity and the second microcavity.

10. The apparatus of any one of claims 4-7, wherein, The first DFB laser and the second DFB laser adopt InP laser chips, the first microcavity chip and the second microcavity chip adopt silicon nitride microcavity chips, the first waveguide chip and the second waveguide chip adopt lithium niobate waveguide chips, end-to-end direct coupling is adopted for coupling between the InP laser chips, the silicon nitride microcavity chips and the lithium niobate waveguide chips, and the packaging integration or hetero integration is adopted to integrate in a tube shell.

Images