On-chip time frequency transmission system and method based on octave optical comb and electro-optical modulation optical comb, and photonic integrated chip

Abstract

The invention discloses an on-chip time-frequency transmission system and method based on an octave optical comb and an electro-optical modulation optical comb, and the method comprises the steps: constructing a chip-based optical reference cavity through the technologies of vacuum optical cement, photoresist backflow and the like, and achieving an on-chip ultra-stable laser through a phase modulator and a reflection separation optical path; an on-chip laser source pumping micro-ring resonant cavity is utilized to generate an octave optical frequency comb, frequency multiplication is carried out on the on-chip laser source pumping micro-ring resonant cavity and an additional laser source to realize detection and locking of carrier envelope offset frequency (fceo), frequency beating is carried out on the on-chip laser source pumping micro-ring resonant cavity and the on-chip ultra-stable laser device to realize frequency beating (fbeam) locking, and the laser source is utilized to generate an electro-optical modulation optical frequency comb through a circulating phase modulator to realize frequency beating and locking of the on-chip ultra-stable laser device. And the optical time frequency is locked with the locked octave optical comb, is sent to a far end after polarization control and light amplification, and simultaneously receives an electro-optical modulation optical comb at the far end and performs linear light sampling, so that the transmission of the optical time frequency is realized. The optical fiber or space optical link time-frequency transmission device can realize optical fiber or space optical link time-frequency transmission, and has the advantages of low overall noise, high transmission precision, compact structure, small size, low power consumption and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of on-chip time-frequency transfer technology, and particularly relates to an on-chip time-frequency transfer system and method based on an octave optical comb and an electro-optical modulation optical comb and a photonic integrated chip. BACKGROUND

[0002] With the continuous maturity of femtosecond optical frequency combs, linear optical sampling technology based on it has gradually developed. By beating two optical frequency combs with a small repetition frequency difference, the beat signal of the output is detected and processed to indirectly obtain the measured information. Due to the high stability of the locked optical frequency comb, the precision of linear optical sampling is extremely high, and it is widely used in the fields of optical spectrum measurement, distance measurement and time-frequency transfer.

[0003] At present, the stability of the optical clock in the laboratory has reached 10 -19 @order of magnitude, and high-precision clocks play an important role in the fields of fundamental physics, precision measurement, positioning and navigation. Linear optical sampling technology based on optical frequency combs has great advantages in time-frequency transfer due to its extremely high precision. In 2013, F.R.Giorgetta et al. obtained a time resolution of 1 fs and a transfer stability of 10 -18 @1000s based on a femtosecond optical frequency comb by using an optical two-way time and frequency transfer method, see [Giorgetta F R, Swann W C, Sinclair L C, et al. Optical two-way time and frequency transfer over free space. Nature Photonics, 2013, 7(6): 434-438.].

[0004] The integration of the optical frequency comb-based time-frequency transfer system on a chip using photonic integration technology can reduce the impact of out-of-band noise and reduce the size and power consumption of the system. However, how to obtain a stable optical frequency comb on a chip is a problem that needs to be solved. In recent years, the development of Kerr optical frequency combs, integrated ultra-stable lasers on a chip, and integrated electro-optic modulation optical frequency combs provides a solution to this problem. See [Zang J, Liu H, Briles T C, et al. Foundry manufacturing of octave-spanning microcombs. Optics letters, 1124, 49(18): 4.][Cheng H, Xiang C, Jin N, et al. Harnessing micro-Fabry-Perot reference cavities in photonic integrated circuits. arXiv preprint arXiv:2410.01095, 1124.][Zhang T, Yin K, Zhang C, et al. Integrated Electro-Optic Frequency Combs: Theory and Current Progress. Laser & Photonics Reviews, 1124, 18(6): 2116363.].

[0005] Although the above-mentioned technology has made significant progress, the existing scheme still has the following problems:

[0006] High complexity of optical frequency comb locking: octave-spanning optical frequency combs need to rely on external laser frequency multiplication and complex feedback systems to achieve self-reference locking, while electro-optic modulation optical frequency combs lack self-locking capability.

[0007] Insufficient system integration: existing time-frequency transfer systems mostly use discrete components, making it difficult to achieve full-chip integration, resulting in large size and high power consumption.

[0008] Limited link adaptability: the dispersion effect in the optical fiber link and the Doppler frequency shift in the spatial link require additional compensation mechanisms, and the existing on-chip system lacks sufficient support. SUMMARY

[0009] The present application aims to solve the problems of the prior art and work, and provides a chip-based time-frequency transfer method based on octave-spanning optical comb and electro-optic modulation optical comb. By self-referencing the octave-spanning optical frequency comb on a chip and locking it to the ultra-stable laser on a chip, and then locking the electro-optic modulation optical frequency comb on a chip to the locked octave-spanning optical frequency comb, a stable electro-optic modulation optical frequency comb is obtained, and time-frequency transfer is achieved.

[0010] To achieve the above object, the technical solution of the present application is as follows:

[0011] In one aspect, the present application provides a method for locking an on-chip electro-optically modulated optical frequency comb, characterized in that it comprises: a first laser, a first micro-ring resonator, a first cyclic phase modulator, a first dispersion compensator, a first linear optical sampling, a first polarization controller, a first bidirectional optical amplifier, a first wavelength division multiplexer 108, a first photodetector, a second photodetector, a second laser, a first frequency-doubling waveguide, a second wavelength division multiplexer, a third photodetector, a fourth photodetector, a third laser, a first phase modulator, a first reflection separation optical path, a first optical reference cavity, a fifth photodetector, and a sixth photodetector;

[0012] First, the on-chip octave optical frequency comb is locked, specifically: the output port of the first laser is connected to the input port of the first micro-ring resonator, and by finely controlling the output frequency of the laser, the micro-ring resonator is pumped to generate an octave Kerr optical frequency comb. This octave optical frequency comb needs to be stabilized at f ceo with a repetition frequency f rep Since the repetition frequency of the octave optical frequency comb is very high, the pulse peak is weak and the noise is high, and it cannot be self-referenced and locked alone, so it needs to be frequency-doubled through the frequency-doubling waveguide at the same time as the second laser. After passing through the second wavelength division multiplexer, f ceo is detected by the third photodetector and the fourth photodetector, and is locked;

[0013] The first optical reference cavity based on the chip is constructed using vacuum optical glue, photoresist reflow, etc. The third laser generates a Pound-Drever-Hall (PDH) signal sideband through the first phase modulator, is incident into the first optical reference cavity through the first reflection separation optical path, and a PDH error signal from the first optical reference cavity is detected by the fifth photodetector. The third laser is locked to the first optical reference cavity to generate ultra-stable laser, which beats with one comb tooth of the octave optical frequency comb, and f beat is detected by the sixth photodetector and is locked. Thus, the octave optical frequency comb generated by the first laser is completely locked;

[0014] Further, the on-chip electro-optically modulated optical frequency comb is locked on the octave optical frequency comb, specifically: the output port of the first laser is connected to the input port of the first cyclic phase modulator, and an electro-optically modulated optical frequency comb is generated through the first cyclic phase modulator. The electro-optically modulated optical frequency comb has a narrow spectrum, so it cannot be self-referenced and locked f ceoTherefore, it is necessary to lock the same with the locked octave optical frequency comb, the electro-optical modulation optical frequency comb generated by the first cyclic phase modulator and the octave optical frequency comb generated by the first micro-ring resonant cavity enter a first wavelength division multiplexer together, two beat signals are detected by a first photoelectric detector and a second photoelectric detector and are locked, and thus the locked electro-optical modulation optical frequency comb is generated.

[0015] In another aspect, the application also provides a method for time-frequency transfer by using the above-mentioned locked electro-optical modulation optical frequency comb, and the method comprises the following steps:

[0016] The time and frequency transfer are performed by linear optical sampling with the first linear optical sampling and the remote electro-optical modulation optical frequency comb.

[0017] When the time-frequency transfer is performed on an optical fiber link, the dispersion in the optical fiber link is compensated by the first dispersion compensator, and when the time-frequency transfer is performed on a space link, the frequency of the first laser is controlled to realize Doppler compensation by the first linear optical sampling of the received electro-optical modulation optical frequency comb signal.

[0018] A photonic integrated chip integrates the above-mentioned on-chip time-frequency transfer system and is used for realizing high-stability time and frequency signal generation and transfer.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] 1) The application provides a method for locking an on-chip electro-optical modulation optical frequency comb, and the locking of the on-chip electro-optical modulation optical frequency comb can be realized by means of the locked octave optical frequency comb, without self-reference of the electro-optical modulation optical frequency comb.

[0021] 2) The cyclic phase modulator, the micro-ring resonant cavity, the phase modulator, the wavelength division multiplexer, the octave waveguide and the like of the application can be realized by on-chip integration, for example, the photonic chip can be selected on lithium niobate integrated on an insulator, and has the advantages of low noise, low power consumption, small size and the like.

[0022] 3) The application utilizes the locked electro-optical modulation optical frequency comb to simultaneously transfer time and frequency signals, can compensate the dispersion of the link by means of a dispersion compensator, and can detect and compensate the Doppler frequency shift by means of linear optical sampling, and has the advantages of high transfer precision and the like. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of an on-chip time-frequency transfer system of the application based on an octave optical comb and an electro-optical modulation optical comb. DETAILED DESCRIPTION

[0024] The application will be further described in conjunction with the embodiments and drawings. The embodiments are implemented on the basis of the technical solutions of the application, and detailed implementation manners and specific work flows are given, but the protection scope of the application is not limited to the following embodiments.

[0025] Please refer to Figure 1 , Figure 1 is an on-chip time-frequency transfer system schematic diagram based on an octave light comb and an electro-optical modulation light comb. The block 1 is an on-chip time-frequency transfer chip structure schematic diagram based on an octave light comb and an electro-optical modulation light comb. As shown in the figure, an on-chip time-frequency transfer chip system based on an octave light comb and an electro-optical modulation light comb comprises a first laser 101, a first micro-ring resonant cavity 102, a first cyclic phase modulator 103, a first dispersion compensator 104, a first linear optical sampling 105, a first polarization controller 106, a first bidirectional optical amplifier 107, a first wavelength division multiplexer 108, a first photoelectric detector 109, a second photoelectric detector 110, a second laser 111, a first octave waveguide 112, a second wavelength division multiplexer 113, a third photoelectric detector 114, a fourth photoelectric detector 115, a third laser 116, a first phase modulator 117, a first reflection separation optical path 118, a first optical reference cavity 119, a fifth photoelectric detector 120, and a sixth photoelectric detector 121.

[0026] The output port of the first laser 101 is connected with the input port of the first micro-ring resonant cavity 102, and the output port of the first laser 101 is also connected with the input port of the first cyclic phase modulator 103. The output port of the first micro-ring resonant cavity 102 is connected with the input port of the first wavelength division multiplexer 108, and the output port of the first micro-ring resonant cavity 102 is also connected with the input port of the first octave waveguide 112 and the input port of the fifth photoelectric detector 121. The output port of the first cyclic phase modulator 103 is connected with the input port of the first dispersion compensator 104, and the output port of the first cyclic phase modulator 103 is also connected with the input port of the first wavelength division multiplexer 108. The output port of the first wavelength division multiplexer 108 is connected with the first photoelectric detector 109 and the second photoelectric detector 110. The output port of the first dispersion compensator 104 is connected with the first linear optical sampling 105. The first linear optical sampling 105 is connected with the first polarization controller 106. The first polarization controller 106 is connected with the first bidirectional optical amplifier 107. The first bidirectional optical amplifier 107 outputs optical signals and receives optical signals at the same time.

[0027] The output port of the second laser 111 is connected with the input port of the first frequency doubling waveguide 112, the output port of the first frequency doubling waveguide 112 is connected with the input port of the first wavelength division multiplexer 113, the output port of the first wavelength division multiplexer 113 is connected with the input port of the third photoelectric detector 114 and the fourth photoelectric detector 115 respectively;

[0028] The output port of the third laser 116 is connected with the input port of the sixth photoelectric detector 121, and the output port of the third laser 116 is connected with the input port of the first phase modulator 117, the output port of the first phase modulator 117 is connected with the first reflection separation light path 118, and the first reflection separation light path 118 is connected with the input port of the first optical reference cavity 119 and the fifth photoelectric detector 120.

[0029] The output of the first laser 101 pumps the micro-ring resonator cavity 102 to generate an octave optical frequency comb, and locks f ceo And the laser 116 locked in the optical reference cavity 119, using the first laser 101 through the cyclic phase modulator 103 to generate an electro-optic modulation optical frequency comb, and lock the octave optical comb after locking, specifically:

[0030] The output port of the first laser 101 is connected with the input port of the first micro-ring resonator cavity 102, and by finely controlling the output frequency of the laser 101, the micro-ring resonator cavity 102 is pumped to generate an octave Kerr optical frequency comb;

[0031] The output light of the second laser 111 is doubled through the first frequency doubling waveguide 112, and after passing through the second wavelength division multiplexer 113, it is detected by the third photoelectric detector 114 and the fourth photoelectric detector 115 f ceo And lock;

[0032] The first optical reference cavity 119 based on the chip is constructed by using vacuum optical glue, photoresist reflow and other technologies, the output light of the third laser 116 is modulated by the first phase modulator 117 to generate a PDH signal sideband and a frequency shift bias sideband, and is incident into the first optical reference cavity 119 through the first reflection separation light path 118, and the PDH error signal from the first optical reference cavity 119 is detected by the fifth photoelectric detector 120, and the third laser 116 is locked to the first optical reference cavity 119 to generate super-stable laser, which beats with one comb tooth of the octave optical frequency comb, and the f beat Signal is detected by the sixth photoelectric detector 121 and locked, so that the octave optical frequency comb generated by the first laser 101 is completely locked;

[0033] The output port of the first laser 101 is connected with the input port of the first cyclic phase modulator 103, and the first cyclic phase modulator 103 is used for modulating to generate an electro-optical modulation optical frequency comb, which is narrow in spectrum and cannot be self-referenced to lock f ceo Therefore, it is necessary to lock it with the locked octave optical frequency comb. The electro-optical modulation optical frequency comb generated by the first cyclic phase modulator 103 and the octave optical frequency comb generated by the first micro-ring resonator cavity 102 enter the first wavelength division multiplexer 108 together, and two beat signals are detected by the first photodetector 109 and the second photodetector 110 and locked, thereby generating a locked electro-optical modulation optical frequency comb.

[0034] Figure 1 A spatial high-precision time-frequency transfer system is shown as a whole, which includes a local end 1, a spatial link 2 and a user end 3. The local end 1 includes a first laser 101, a first micro-ring resonator cavity 102, a first cyclic phase modulator 103, a first dispersion compensator 104, a first linear optical sampling 105, a first polarization controller 106, a first bidirectional optical amplifier 107, a first wavelength division multiplexer 108, a first photodetector 109, a second photodetector 110, a second laser 111, a first frequency-doubling waveguide 112, a second wavelength division multiplexer 113, a third photodetector 114, a fourth photodetector 115, a third laser 116, a first phase modulator 117, a first reflection separation optical path 118, a first optical reference cavity 119, a fifth photodetector 120 and a sixth photodetector 121. The user end 3 includes a first laser 116, a first micro-ring resonator cavity 117, a first cyclic phase modulator 118, a first dispersion compensator 119, a first linear optical sampling 120, a first polarization controller 121, a first bidirectional optical amplifier 307, a first wavelength division multiplexer 308, a first photodetector 309, a second photodetector 310, a second laser 311, a first frequency-doubling waveguide 312, a second wavelength division multiplexer 313, a third photodetector 314, a fourth photodetector 315, a third laser 316, a first phase modulator 317, a first reflection separation optical path 318, a first optical reference cavity 319, a fifth photodetector 320 and a sixth photodetector 321.

[0035] An on-chip time-frequency transfer method based on an octave optical comb and an electro-optical modulation optical comb includes the following steps:

[0036] 1) Generation and locking of an octave optical frequency comb:

[0037] At local end 1, the first laser 101, using a center wavelength of 1550nm, pumps the first microring resonator 102 to generate an octave band optical frequency comb. Stable octave band optical frequency comb output is obtained by precisely adjusting the laser temperature and thermally tuning the microring resonator. The frequency of the nth tooth of this octave band optical frequency comb... for:

[0038]

[0039] in, The carrier envelope offset frequency of the optical frequency comb. Let n be the repetition frequency of the optical frequency comb, where n is an integer.

[0040] The second laser 111 uses a center wavelength of 2200nm, and its frequency is denoted as f. 2200 After beating the octave band optical frequency comb, the beat frequency signal Δ is obtained. 2200 :

[0041]

[0042] Where m is an integer.

[0043] After passing through the first frequency harmonic waveguide and frequency harmonicized by 112, we have:

[0044]

[0045] At the same time, f 2200 Frequency multiplied by f 1100 Frequency doubling light f 1100 After beating the frequency with an octave band optical frequency comb, the beat frequency signal Δ1100 is obtained, which is:

[0046]

[0047] The frequency-doubled and unfrequency-doubled light are passed through the second wavelength division multiplexer 113, and then beat and detected on the third photodetector 114 and the fourth photodetector 115, respectively, to generate a difference-frequency optical heterodyne signal:

[0048] Δ 2f-f =2f 2200 -f 1100

[0049] Related to the beat frequency of the octave band optical frequency comb and the second laser 111:

[0050]

[0051] Lock Δ 2200 =10MHz and Δ 2f-f =20MHz, since it is an octave band optical frequency comb, 2m-n=0, therefore:

[0052]

[0053] The detected, it can be locked at a particular frequency.

[0054] The first optical reference cavity 119 is constructed based on the chip using vacuum photoresist, photoresist reflow and other technologies, the third laser 116 is modulated by the first phase modulator 117 to produce Pound-Drever-Hall (PDH) signal sideband and frequency shift bias sideband, through the first reflection separation optical path 118 into the first optical reference cavity 119, and the fifth photodetector 120 is used to detect the PDH error signal from the first optical reference cavity 119, and the third laser 116 is locked to the first optical reference cavity 119 to generate ultra-stable laser, the laser wavelength of which is 1560nm, and the frequency is f 1560 The frequency of one comb tooth of the octave optical frequency comb is detected by the sixth photodetector 121, and the Δ b signal is locked, which is expressed as:

[0055]

[0056] Wherein, p is an integer. Locking Δ beat = 20MHz, since has been locked, so is also locked, and the octave optical frequency comb is completely locked.

[0057] 2) Generation and locking of electro-optically modulated optical frequency comb:

[0058] Further, the on-chip electro-optically modulated optical frequency comb is locked on the octave optical frequency comb, specifically: the output port of the first laser 101 is connected with the input port of the first cyclic phase modulator 103, and the first cyclic phase modulator 103 is modulated to generate an electro-optically modulated optical frequency comb, which can be expressed as:

[0059]

[0060] Wherein, is the frequency of the nth comb tooth of the electro-optically modulated optical frequency comb, is the carrier envelope offset frequency of the optical frequency comb, is the repetition frequency of the optical frequency comb, and n is an integer.

[0061] The electro-optically modulated optical frequency comb spectrum is narrow, so it cannot be self-referenced and locked Therefore, it is necessary to lock it with the locked octave optical frequency comb, the electro-optical modulation optical frequency comb generated by the first cyclic phase modulator 103 is combined with the octave optical frequency comb generated by the first micro-ring resonator cavity 102 to enter the first wavelength division multiplexer 108, and the two beat signals Δ1 and Δ2 are detected by the first photoelectric detector 109 and the second photoelectric detector 110, which can be expressed as:

[0062]

[0063] Wherein, m1, m2, n1, n2 are integers.

[0064] Lock Δ1 and Δ2, that is, lock And Thus, the locked electro-optical modulation optical frequency comb is generated and transmitted to the user end 3 through the spatial optical link 2.

[0065] 3) Optical time frequency transfer

[0066] The user end 3 is the same as the local end 1, and the first laser 116 pumps the first micro-ring resonator cavity 117 to generate an octave optical frequency comb, which is multiplied by the additional second laser 311 to realize Detection and locking, and the beat frequency Δ is realized by beating the super-stable laser generated by the third laser 316 locked in the first optical reference cavity 319. beat Locking. The first laser 116 generates an electro-optical modulation optical frequency comb through a cyclic phase modulator, which is locked with the locked octave optical comb, and is transmitted to the local end 1 through the spatial optical link 2.

[0067] There is a small repetition frequency difference between the stable electro-optical modulation optical frequency comb from the local end 1 and the stable electro-optical modulation optical frequency comb from the user end 3, which is input into the photoelectric detector in the linear optical sampling 105 and 120 after transmission through the spatial optical link 2. Since the electro-optical modulation optical frequency comb of the local end 1 and the user end 3 is locked at a certain frequency, which can come from the local and user optical atomic clocks, assuming that the clock difference causes the deviation of their initial pulse time, which is set as ΔT 13 (τ). When the light from the local end 1 is incident on the user end 3, according to the principle of linear optical sampling, the calculated ΔT phase (τ) is the time difference of their initial pulses, considering the link delay of the spatial optical link 2, so assuming that the calculation result of the linear optical sampling of the local end 1 is ΔT1(τ), then:

[0068] ΔT1(τ) = ΔT2(τ) + ΔT 13 (τ)

[0069] Where ΔT2(τ) is the time difference caused by the space optical link 2, so that the time difference between the two places is calculated at the local end 1, which contains the respective clock difference and the result of the link delay. Similarly, since the link is bidirectional, the optical comb of the local end 1 is incident on the user end 3, and ΔT3(τ) is also calculated at the user end 3, which has the following relationship

[0070] ΔT3(τ) = ΔT2(τ) - ΔT 13 (τ)

[0071] After calculating the time difference at A and B respectively, the difference between the calculation results is obtained, so that the influence of the link can be eliminated, and the clock difference is obtained. Since the optical frequency comb of the electro-optical modulator is almost at the same time, the error caused by the link jitter can be greatly eliminated, and since the time measurement accuracy of linear optical sampling is in the order of fs, the final clock difference measurement result can provide very high precision.

[0072] Therefore, using the above-mentioned on-chip time-frequency transfer system based on octave optical comb and electro-optical modulation optical comb, high-precision optical time-frequency transfer can be realized.

Claims

1. An on-chip time-frequency transfer system based on an octave band optical comb and an electro-optic modulation optical comb, characterized in that, include: The system comprises a first laser (101), a first micro-ring resonator (102), a first cyclic phase modulator (103), a first dispersion compensator (104), a first linear light sampler (105), a first polarization controller (106), a first bidirectional optical amplifier (107), a first wavelength division multiplexer (108), a first photodetector (109), a second photodetector (110), a second laser (111), a first frequency doubling waveguide (112), a second wavelength division multiplexer (113), a third photodetector (114), a fourth photodetector (115), a third laser (116), a first phase modulator (117), a first reflection-separating optical path (118), a first optical reference cavity (119), a fifth photodetector (120), and a sixth photodetector (121). The output port of the first laser (101) is connected to the input port of the first micro-ring resonator (102), and simultaneously the output port of the first laser (101) is connected to the input port of the first cyclic phase modulator (103). The output port of the first micro-ring resonator (102) is connected to the input port of the first wavelength division multiplexer (108), and simultaneously the output port of the first micro-ring resonator (102) is connected to the input port of the first frequency doubling waveguide (112), and simultaneously the output port of the first micro-ring resonator (102) is connected to the input port of the fifth photodetector (121). The output port of the first cyclic phase modulator (103) is connected to the input port of the first dispersion compensator (104). The input is connected, and the output port of the first cyclic phase modulator (103) is connected to the input port of the first wavelength division multiplexer (108). The output port of the first wavelength division multiplexer (108) is connected to the first photodetector (109) and the second photodetector (110). The output port of the first dispersion compensator (104) is connected to the first linear optical sampler (105). The first linear optical sampler (105) is connected to the first polarization controller (106). The first polarization controller (106) is connected to the first bidirectional optical amplifier (107). The first bidirectional optical amplifier (107) is used to output optical signals to the remote link and receive optical signals from the remote link. The output port of the second laser (111) is connected to the input port of the first frequency doubling waveguide (112), the output port of the first frequency doubling waveguide (112) is connected to the input port of the first wavelength division multiplexer (113), and the output port of the first wavelength division multiplexer (113) is connected to the input ports of the third photodetector (114) and the fourth photodetector (115), respectively. The output port of the third laser (116) is connected to the input port of the sixth photodetector (121). At the same time, the output port of the third laser (116) is connected to the input port of the first phase modulator (117). The output port of the first phase modulator (117) is connected to the first reflection separation optical path (118). The first reflection separation optical path (118) is connected to the input ports of the first optical reference cavity (119) and the fifth photodetector (120).

2. The on-chip time-frequency transfer system based on an octave band optical comb and an electro-optic modulation optical comb according to claim 1, characterized in that, The system is fully integrated on a photonic chip, which is manufactured using lithium niobate-on-insulator (LNOI) or silicon-based photonic integration technology.

3. The on-chip time-frequency transfer system based on an octave band optical comb and an electro-optic modulation optical comb according to claim 1, characterized in that, The first optical reference cavity (119) is an on-chip integrated optical cavity fabricated based on vacuum photoresist and photoresist reflow technology, used to provide a highly stable optical frequency reference.

4. The on-chip time-frequency transfer system based on an octave band optical comb and an electro-optic modulation optical comb according to claim 1, characterized in that, The first micro-ring resonant cavity (102) controls its resonant frequency by thermal tuning or electrical tuning to generate a stable octave band Kerr optical frequency comb.

5. The on-chip time-frequency transfer system based on an octave band optical comb and an electro-optic modulation optical comb according to claim 1, characterized in that, The first cyclic phase modulator (103) is a lithium niobate electro-optic modulator, used to generate an electro-optic modulated optical frequency comb, and to achieve frequency locking by beating the locked octave band optical comb.

6. An on-chip time-frequency transfer method based on the system of any one of claims 1-5, characterized in that, Includes the following steps: S1. Generation and locking of octave band optical frequency comb: The pump light output from the first laser (101) is input into the first micro-ring resonator (102) to generate an octave band optical frequency comb; The light output from the second laser (111) is frequency-doubled by the first frequency-doubled waveguide (112) and then combined with the double-band optical frequency comb in the second wavelength division multiplexer (113). The beat frequency signal is detected by the third photodetector (114) and the fourth photodetector (115) to lock the carrier envelope offset frequency f. ceo ; The light output from the third laser (116) is modulated by the first phase modulator (117) to generate a PDH signal sideband and a frequency shift bias sideband. This light is then incident on the first optical reference cavity (119) through the first reflection-separation optical path (118). The fifth photodetector (120) detects the PDH error signal from the first optical reference cavity (119), locking the third laser (116) onto the first optical reference cavity (119) to generate an ultra-stable laser. This ultra-stable laser beats one tooth of an octave band optical frequency comb. The beat signal is detected by the sixth photodetector (121), locking the repetition frequency f. beat Thus, the octave band optical frequency comb generated by the first laser (101) is completely locked; S2. Generation and locking of electro-optic modulated optical frequency comb: The light output from the first laser (101) is modulated by the first cyclic phase modulator (103) to generate an electro-optic modulated optical frequency comb, which is combined with the locked octave band optical comb in the first wavelength division multiplexer (108). The beat frequency signal is detected by the first photodetector (109) and the second photodetector (110) to achieve frequency locking. S3. Transmission and compensation of time-frequency signals: After the locked electro-optic modulated optical comb is compensated for dispersion by the first dispersion compensator (104), it is transmitted to the remote link in sequence through the first linear optical sampling module (105), the first polarization controller (106) and the first bidirectional optical amplifier (107); Simultaneously, the return optical signal from the remote link is received, and Doppler frequency shift compensation is performed through the first linear optical sampling module (105), and the link time difference is measured to achieve high-precision time-frequency synchronization.

7. The on-chip time-frequency transfer method according to claim 6, characterized in that, In the optical fiber link, the dispersion in the optical fiber link is compensated by the first dispersion compensator (104); when in the space link, the Doppler compensation is achieved by receiving the electro-optic modulated optical frequency comb signal transmitted from the remote end, performing linear optical sampling by the first linear optical sampler (105), and controlling the frequency of the first laser (101).

8. A photonic integrated chip, characterized in that, The on-chip time-frequency transfer system according to any one of claims 1-5 is integrated to achieve highly stable generation and transmission of time and frequency signals.

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