Starting-key-based soliton micro-comb multi-line multiplexing system and control method

Abstract

The invention provides a start key type soliton micro-comb multi-line multiplexing system and a control method, and the system comprises a first soliton micro-comb generation and control module, a second soliton micro-comb generation and control module, a distance measurement module, a gas spectrum analysis module, a communication module and a processing module. The first soliton micro-comb generation and control module and the second soliton micro-comb generation and control module respectively generate a first soliton optical frequency comb and a second soliton optical frequency comb; the distance measurement module, the gas spectral analysis module and the communication module respectively output distance measurement data, gas spectral analysis data, a modulation signal and a local oscillation signal based on the first soliton optical frequency comb and the second soliton optical frequency comb; and the processing module receives the distance measurement data, the gas spectral analysis data, the modulation signal and the local oscillation signal and outputs a distance measurement result, a gas spectral analysis result and a modulation result. The system is simple in structure and operation, narrow in laser line width and excellent in performance, has no special requirements on the environment, and has reliability and robustness.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated photonics and precision measurement, and in particular to a multi-line multiplexing system based on a key-on soliton microcomb and a control method. BACKGROUND

[0002] With the continuous development of integrated photonics and optical frequency comb technology, miniaturized, low-power and high-performance optical systems have become a core device urgently needed in the fields of precision measurement, spectral analysis and high-speed communication. As a new generation of low-noise and high-repetition-rate optical frequency comb source, the soliton microcomb has the advantages of compact structure, low power consumption and easy integration, and has become one of the hot research directions of optical frequency comb. Soliton microcomb can spontaneously generate stable equidistant frequency comb lines using the Kerr nonlinear effect in a high-Q factor microcavity, and can realize precise conversion from the optical domain to the microwave domain, and is widely used in frequency synthesis, precise spectral measurement, absolute distance measurement and other fields.

[0003] In the development process of soliton microcomb, the traditional soliton microcomb system often has high requirements for experimental conditions and needs complex tuning process, which is difficult to meet the needs of portable and multifunctional integrated applications. Key-on soliton microcomb can realize rapid and automatic starting of soliton state by using self-injection locking effect, which significantly reduces the operation complexity and improves the practicability and stability of the system.

[0004] On the other hand, with the continuous integration of precision measurement, environmental monitoring, gas detection and high-speed communication technology, there is an increasing demand for high-integration, multi-function and multiplexing optical systems. Traditional solutions are usually independent systems, which cannot realize resource sharing and system integration, resulting in large size, high power consumption and high cost. SUMMARY

[0005] The present application provides a multi-line multiplexing system based on a key-on soliton microcomb and a control method to solve the problem of being unable to realize resource sharing and system integration, resulting in large size, high power consumption and high cost.

[0006] In a first aspect, the present application provides a multi-line multiplexing system based on a key-on soliton microcomb, comprising:

[0007] A first soliton microcomb generation and control module, comprising a first soliton microcomb generation device, a first optical fiber cavity and a first adjustable current source, the first optical fiber cavity is used to generate a transmitted optical signal, the first adjustable current source is used to receive the transmitted optical signal to generate a self-injection locking key-on mechanism, the self-injection locking key-on mechanism is used to trigger the first soliton microcomb generation device to output a first soliton optical frequency comb;

[0008] The second soliton microcomb generation and control module comprises a second soliton microcomb generation device, a second fiber cavity for generating a transmitted light signal, and a second adjustable current source for receiving the transmitted light signal to generate a self-injection locking key-on mechanism for triggering the second soliton microcomb generation device to output a second soliton optical frequency comb.

[0009] The first soliton optical frequency comb and the second soliton optical frequency comb are optical frequency combs with a preset frequency interval.

[0010] The distance measurement module receives the first soliton optical frequency comb and the second soliton optical frequency comb, generates a first interference signal through a reflection light path, and performs distance measurement through the first interference signal to output distance measurement data.

[0011] The gas spectrum analysis module receives the first soliton optical frequency comb and the second soliton optical frequency comb, generates a second interference signal using a gas cell, and performs gas absorption spectrum analysis through the second interference signal to output gas spectrum analysis data.

[0012] The communication module transmits the first soliton optical frequency comb and the second soliton optical frequency comb through terahertz communication to generate a terahertz electromagnetic wave, and generates a modulation signal and a local oscillator signal for communication transmission based on the terahertz electromagnetic wave.

[0013] The processing module receives the distance measurement data to output distance measurement results, receives the gas spectrum analysis data to output gas spectrum analysis results, and receives the modulation signal and the local oscillator signal to output modulation results.

[0014] In some possible embodiments, the first soliton microcomb generation and control module further comprises:

[0015] The semiconductor laser is used to generate pump light.

[0016] The first adjustable current source is connected to the semiconductor laser to control the output power of the pump light through adjustable current to output pump light with a preset power.

[0017] The polarization beam splitter is used to couple the pump light with a preset power to the first soliton microcomb generation device and receive the transmitted light of the pump light.

[0018] The silicon wafer is used to receive the transmitted light and adjust the phase of the transmitted light to output adjusted transmitted light.

[0019] The voltage source applies adjustable voltage to the silicon wafer.

[0020] a first soliton microcomb generation device, configured to generate a first equidistant frequency comb under excitation of the preset power pump light;

[0021] a spectrometer, configured to detect a spectrum of the first equidistant comb, and lock output parameters of the adjustable current source and the voltage source to generate a first soliton optical frequency comb when the spectrometer detects the spectrum.

[0022] In some possible embodiments, the distance measurement module comprises:

[0023] a first coupler, configured to split the first soliton optical frequency comb into a probe light beam and a reference light beam;

[0024] a circulator, comprising a first port, a second port and a third port, the first port is connected to the probe light beam, the second port is connected to a collimator, the collimator is configured to collimate the probe light beam to be incident on a surface of a detected object, and receive a reflected light beam through a coaxial path, and the third port is configured to send the reflected light beam to a second coupler;

[0025] the second coupler is configured to combine the reference light beam and the reflected light beam to output a combined light signal;

[0026] a first polarization controller, configured to adjust a polarization state of the first soliton optical frequency comb;

[0027] a second polarization controller, configured to adjust a polarization state of the second soliton optical frequency comb;

[0028] a third coupler, configured to perform optical field mixing on the combined light signal and the second soliton optical frequency comb to output an interference optical field;

[0029] a first photodetector, configured to convert the interference optical field into a beat frequency electrical signal containing distance phase information;

[0030] a first oscilloscope, configured to acquire the beat frequency electrical signal and output distance measurement data.

[0031] In some possible embodiments, the gas spectrum analysis module comprises:

[0032] a third polarization controller, configured to adjust a polarization state of the first soliton optical frequency comb;

[0033] a fourth polarization controller, configured to adjust a polarization state of the second soliton optical frequency comb;

[0034] a fourth coupler, configured to split the first soliton optical frequency comb into a first light beam and a second light beam;

[0035] a sixth coupler, configured to split the second soliton optical frequency comb into a third light beam and a fourth light beam;

[0036] a fifth coupler configured to combine the first light beam and the third light beam to output a first combined light beam;

[0037] a gas cell configured to perform gas molecule absorption on the fourth light beam to output an absorption signal;

[0038] a second photodetector configured to receive the first combined light beam and convert it into a first electrical signal;

[0039] a seventh coupler configured to combine the second light beam and the absorption signal to output a second combined light beam;

[0040] a third photodetector configured to receive the second light beam and the second combined light beam and convert them into a second electrical signal;

[0041] a second oscilloscope configured to collect the first electrical signal and the second electrical signal to output gas spectrum analysis data.

[0042] In some possible embodiments, the second oscilloscope is configured to collect the first electrical signal and the second electrical signal, extract frequency difference information by Fourier transform or spectrum analysis, and the frequency difference information is the gas spectrum analysis data.

[0043] In some possible embodiments, the communication module comprises:

[0044] a first waveform shaper configured to perform filtering processing on the first soliton optical frequency comb to separate a first carrier wavelength from a first local oscillator wavelength;

[0045] a modulator configured to load communication data on the first carrier wavelength to generate loaded data;

[0046] an eighth coupler configured to combine the first carrier wavelength of the loaded data and the first local oscillator wavelength to output a dual-wavelength optical signal;

[0047] a first photoelectric conversion unit configured to convert the dual-wavelength optical signal into a terahertz electromagnetic wave;

[0048] a terahertz emission lens configured to radiate the terahertz electromagnetic wave;

[0049] a terahertz receiving lens configured to receive the terahertz electromagnetic wave transmitted in space;

[0050] a second waveform shaper configured to perform filtering processing on the second soliton optical frequency comb to separate a second carrier wavelength from a second local oscillator wavelength;

[0051] a second photoelectric conversion unit configured to convert the second carrier wavelength and the second local oscillator wavelength into a terahertz local oscillator reference signal;

[0052] a mixer, configured to mix the signal output by the terahertz receiving lens with the terahertz local reference signal to output a baseband signal;

[0053] a telecommunication signal amplifier, configured to amplify the baseband signal;

[0054] a first spectrum analyzer, configured to demodulate the amplified baseband signal to output a modulated signal and a local signal.

[0055] In some possible embodiments, the processing module comprises:

[0056] a first processing module, configured to receive the distance measurement data, and output a distance measurement result by a ranging inversion algorithm;

[0057] a second processing module, configured to receive the gas spectrum analysis data, and output a gas spectrum analysis result by a spectrum recognition algorithm;

[0058] a third processing module, configured to receive the modulated modulated signal and local signal, and output a modulation result by demodulating the modulated signal by a communication algorithm, the modulation result at least comprising a bit error rate and a constellation diagram.

[0059] In some possible embodiments, the first optical fiber cavity and the second optical fiber cavity are two-mode optical fiber structures, and the free spectral range is a preset range.

[0060] In a second aspect, the present application provides a control method based on a key-on soliton microcomb multi-line multiplexing system, comprising:

[0061] generating a first soliton optical frequency comb and a second soliton optical frequency comb;

[0062] performing distance measurement based on the first soliton optical frequency comb and the second soliton optical frequency comb to output distance measurement data;

[0063] performing gas absorption spectrum analysis based on the first soliton optical frequency comb and the second soliton optical frequency comb to output gas spectrum analysis data;

[0064] transmitting the first soliton optical frequency comb and the second soliton optical frequency comb through terahertz communication to generate modulation data;

[0065] outputting a distance measurement result by the distance measurement data, a gas spectrum analysis result by the gas spectrum analysis data, and a modulation result by the modulation data.

[0066] In some possible embodiments, the generating a first soliton optical frequency comb and a second soliton optical frequency comb comprises:

[0067] The first soliton optical frequency comb with adjustable frequency interval is output by the first soliton microcomb generation device under a self-injection locking key-on mechanism.

[0068] The second soliton optical frequency comb with adjustable frequency interval is output by the second soliton microcomb generation device under a self-injection locking key-on mechanism.

[0069] The generation process of the self-injection locking key-on mechanism comprises:

[0070] The transmission light signal is acquired.

[0071] The self-injection locking key-on mechanism is generated through the transmission light signal.

[0072] According to the above technical solution, the application provides a key-on type soliton microcomb multi-line multiplexing system and a control method. The system comprises a first soliton microcomb generation and control module, a second soliton microcomb generation and control module, a distance measurement module, a gas spectrum analysis module, a communication module, and a processing module. The first soliton microcomb generation and control module and the second soliton microcomb generation and control module generate a first soliton optical frequency comb and a second soliton optical frequency comb, respectively. The distance measurement module performs distance measurement based on the first soliton optical frequency comb and the second soliton optical frequency comb and outputs distance measurement data. The gas spectrum analysis module performs gas absorption spectrum analysis based on the first soliton optical frequency comb and the second soliton optical frequency comb and outputs gas spectrum analysis data. The communication module transmits the first soliton optical frequency comb and the second soliton optical frequency comb through terahertz communication, generates a terahertz electromagnetic wave, and generates a modulation signal and a local oscillator signal for communication transmission based on the terahertz electromagnetic wave. The processing module receives the distance measurement data, the gas spectrum analysis data, and the modulation signal and the local oscillator signal to output distance measurement results, gas spectrum analysis results, and modulation results. The system structure and operation are relatively simple, the laser has low noise and narrow linewidth, the performance is excellent, no special requirements for the environment, easy to use, and has excellent reliability and robustness. BRIEF DESCRIPTION OF DRAWINGS

[0073] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed in the embodiments. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0074] Figure 1 The structure diagram of the key-on type soliton microcomb multi-line multiplexing system provided by the embodiments of the application is shown.

[0075] Figure 2 The structure diagram of the first soliton microcomb generation and control module provided by the embodiments of the application is shown.

[0076] Figure 3 A graph of a first soliton optical frequency comb provided for an embodiment of the present application;

[0077] Figure 4 A graph of a second soliton optical frequency comb provided for an embodiment of the present application;

[0078] Figure 5 A process diagram of a self-injection locking key-on mechanism provided for an embodiment of the present application;

[0079] Figure 6 A key-on result diagram provided for an embodiment of the present application;

[0080] Figure 7 A structure diagram of a distance measurement module provided for an embodiment of the present application;

[0081] Figure 8 A structure diagram of a gas spectrum analysis module provided for an embodiment of the present application;

[0082] Figure 9 A structure diagram of a communication module provided for an embodiment of the present application;

[0083] Figure 10 A distance measurement result diagram provided for an embodiment of the present application;

[0084] Figure 11 A gas spectrum analysis result diagram provided for an embodiment of the present application;

[0085] Figure 12 A bit error rate and constellation diagram provided for an embodiment of the present application.

[0086] Illustration:

[0087] Wherein, 1-first adjustable current source; 2-semiconductor laser; 3-polarization beam splitter; 4-first optical fiber cavity; 5-optical fiber amplifier; 6-beam splitter; 7-optical spectrum analyzer; 8-photoelectric detector; 9-second optical spectrum analyzer; 10-silicon wafer; 11-voltage source; 12-first coupler; 13-circulator; 14-collimator; 15-detection object; 16-second coupler; 17-first polarization controller; 18-second polarization controller; 19-third coupler; 20-first photoelectric detector; 21-first oscilloscope; 22-third polarization controller; 23-fourth coupler; 24-fifth coupler; 25-second photoelectric detector; 26-fourth polarization controller; 27-sixth coupler; 28-gas cell; 29-seventh coupler; 30-third photoelectric detector; 31-second oscilloscope; 32-first waveform shaper; 33-modulator; 34-eighth coupler; 35-optical fiber; 36-first photoelectric conversion unit; 37-terahertz emission lens; 38-terahertz receiving lens; 39-fundamental wave mixer; 40-terahertz amplifier; 41-second photoelectric conversion unit; 42-second waveform shaper; 43-electric amplifier; 44-first optical spectrum analyzer. DETAILED DESCRIPTION

[0088] The embodiments will be described in detail below with reference to examples thereof as illustrated in the accompanying drawings. In the following description, unless otherwise indicated, like numbers in the different figures represent the same or similar elements. The embodiments described in the following examples do not represent all of the implementations consistent with the application. Rather, they are merely examples of systems and methods consistent with some aspects of the application as detailed in the appended claims.

[0089] With the development of integrated photonics and optical frequency comb technology, miniaturized, low-power, high-performance optical systems have become a core device in the fields of precision measurement, spectral analysis, and high-speed communication. Soliton micro-combs, as a new generation of low-noise, high-repetition-rate optical frequency comb source, have the advantages of compact structure, low power consumption, and easy integration, and have become one of the hot research directions in the field of optical frequency comb. Soliton micro-combs can spontaneously generate stable equidistant frequency comb lines using the Kerr nonlinear effect in high-Q microcavities, enabling precise conversion from the optical domain to the microwave domain, and are widely used in frequency synthesis, precision spectral measurement, and absolute distance measurement.

[0090] In the development of soliton micro-combs, traditional soliton micro-comb systems often require high experimental conditions and complex tuning processes, making it difficult to meet the needs of portable, multifunctional integrated applications. Keyed soliton micro-combs use self-injection locking to enable rapid and automatic startup of soliton states, significantly reducing operational complexity and improving system practicality and stability.

[0091] On the other hand, with the continuous integration of precision measurement, environmental monitoring, gas detection and high-speed communication technology, the demand for high integration, multi-functional multiplexing optical system is increasing. The traditional scheme is an independent system, which cannot realize resource sharing and system integration, resulting in large size, high power consumption and high cost. In view of this situation, the present application provides a multi-line multiplexing system based on a key-on small-sized soliton microcomb device, which can realize high-precision distance measurement, gas spectrum analysis and high-speed coherent communication by modular design, and significantly improve the integration and application range of the system.

[0092] The present application not only breaks through the technical bottleneck of soliton microcomb miniaturization and multi-functional integration, but also provides a new technical path and solution for precision measurement, spectrum detection and high-speed communication.

[0093] As shown in Figure 1 The present application provides a multi-line multiplexing system based on a key-on soliton microcomb, which realizes the three modules of ranging, gas spectrum analysis and communication in one system by using two key-on soliton microcomb devices, and has the functions of starting automatically and the like.

[0094] The system includes a first soliton microcomb generation and control module, a second soliton microcomb generation and control module, a distance measurement module, a gas spectrum analysis module, a communication module and a processing module.

[0095] In the soliton microcomb generation and control module, the adjustable voltage source 11 is used to control the output power and frequency of the semiconductor laser 2, and the voltage across the silicon wafer 10 is used to control the phase in the self-injection locking feedback loop, so that the soliton optical frequency comb with a frequency interval of 1-500GHz can be realized. In the distance measurement module, the oscilloscope is used to analyze the interference pattern of the double comb pair ranging signal, and the distance signal is calculated from the sampling signal of multiple periods, which has the characteristics of high precision and fast sampling. In the gas spectrum analysis module, the signal contrast of the double comb interference signal before and after absorption is compared on the oscilloscope, and the absorption of the contrast frequency spectrum after Fourier transform can be corresponded to the gas absorption in the wavelength domain. It has the characteristics of high sensitivity and fast sampling. In the communication module, the UTC-PD is used to convert the optical frequency comb to the terahertz band, and the two soliton optical frequency combs are used as the signal transmitting end and the local oscillator end respectively, which can realize high-speed terahertz communication link without carrier phase estimation, and further realize high signal-to-noise ratio communication transmission.

[0096] The first soliton microcomb generation and control module comprises a first soliton microcomb generation device, a first fiber cavity 4 for generating a transmitted light signal, and a first adjustable current source 1 for receiving the transmitted light signal to generate a self-injection locking key-on mechanism for triggering the first soliton microcomb generation device to output a first soliton optical frequency comb.

[0097] The second soliton microcomb generation and control module comprises a second soliton microcomb generation device, a second fiber cavity for generating a transmitted light signal, and a second adjustable current source for receiving the transmitted light signal to generate a self-injection locking key-on mechanism for triggering the second soliton microcomb generation device to output a second soliton optical frequency comb.

[0098] In this embodiment, the first soliton microcomb generation and control module and the second soliton microcomb generation and control module have the same structure, wherein the first soliton microcomb generation and control module generates a first soliton optical frequency comb, and the second soliton microcomb generation and control module generates a second soliton optical frequency comb. It can be understood that the structure of the first soliton microcomb generation and control module and the process of generating a soliton optical frequency comb are also applicable to the second soliton microcomb generation and control module.

[0099] As shown in Figure 2 In some embodiments, the first soliton microcomb generation and control module further comprises:

[0100] A semiconductor laser 2 is used to generate pump light, and the output power of the pump light is continuously adjustable by changing the injection current, and the power adjustment range covers the critical interval of soliton state generation.

[0101] The first adjustable current source 1 is connected to the semiconductor laser 2, and the output power of the pump light is controlled by the adjustable current to output pump light with a preset power. The output end of the first adjustable current source 1 is connected to the electrode of the semiconductor laser 2, and the current source provides current output and receives adjustment instructions through a digital control interface. The current source converts the external control signal into driving current to make the laser output pump light with a preset power.

[0102] A polarization beam splitter 3 is used to couple the pump light with a preset power to the first soliton microcomb generation device and receive the transmitted light of the pump light. The input end receives the non-polarized pump light emitted by the laser. The polarization beam splitter 3 is coated with a polarization splitting film inside to decompose the incident light into two beams of orthogonal linearly polarized light: P-polarized light is transmitted to the fiber cavity, and S-polarized light is reflected to the monitoring port. The polarization beam splitter 3 has dual functions of optical coupling and power distribution in this module.

[0103] Silicon chip 10 is used to receive the transmitted light and adjust its phase to output adjusted transmitted light. Phase adjustment is achieved through the thermo-optical effect: when a voltage is applied, the temperature of silicon chip 10 increases, causing a corresponding change in its refractive index. Silicon chip 10 receives the transmitted light and modulates its phase. The amount of phase adjustment directly determines whether the feedback light can trigger self-injection locking.

[0104] A voltage source 11 applies an adjustable voltage to the silicon wafer 10, with the positive and negative outputs connected to electrodes on the surface of the silicon wafer 10. The voltage source 11 applies a continuously adjustable voltage between 0 and 10 volts to the silicon wafer 10, and the amplitude of the refractive index change of the silicon wafer 10 is controlled by adjusting the voltage value.

[0105] The first soliton micro-comb generating device is used to generate a first equally spaced frequency comb under the excitation of the preset power pump light; under the excitation of the preset power pump light, the continuous light is converted into a soliton pulse sequence through the Kerr nonlinear effect in the optical fiber, thereby generating a first equally spaced frequency comb with equally spaced comb teeth characteristics.

[0106] Spectrometer 7 is configured to detect the spectrum of the first equally spaced comb teeth. When the spectrometer 7 detects the spectrum of the first equally spaced comb teeth, it locks the output parameters of the adjustable current and voltage sources 11 to generate the first soliton optical frequency comb. Spectrometer 7 is a fiber-coupled optical spectrum analyzer, with its input fiber connected to the transmission end of the fiber cavity. This device monitors the output spectral morphology in real time. When a distribution of equally spaced and uniformly intensified comb teeth is detected in the spectrum, it determines that a soliton state has been generated. At this point, spectrometer 7 sends a lock command to the control system, terminating parameter adjustment of the current and voltage sources 11.

[0107] Among them, the first soliton optical frequency comb and the second soliton optical frequency comb are optical frequency combs with a frequency interval of a preset frequency interval; the first fiber cavity 4 and the second fiber cavity are two-mode fiber structures, and the free spectrum range is a preset range, wherein the preset range is 1GHz-500GHz, and the first fiber cavity 4 and the second fiber cavity are high-Q value fiber ring resonators, and high-reflection dielectric films are fused at both ends, which are used to convert pump light into an equally spaced comb tooth spectrum through the Kerr nonlinear effect.

[0108] First, in the first soliton microcomb generation and control module, by adjusting the adjustable current source to a current range of 1A, the pump light enters polarization beam splitter 3, and the P-polarized component is vertically transmitted through the beam splitter film to the first soliton microcomb generation device. The pump light undergoes multiple reflections within the fiber ring cavity, and when the accumulated nonlinear phase shift reaches a critical threshold, an optical soliton is formed.

[0109] The transmission light outputted from the fiber cavity contains the soliton pulse characteristic signal, and is phase calibrated by the silicon wafer 10. The principle of phase adjustment is based on the temperature rise of the silicon wafer 10 controlled by the voltage source 11, and at the same time, a suitable voltage is applied to the voltage source 11 connected to the silicon wafer 10, and the voltage range can be within 5V. When the voltage of the silicon wafer 10 rises, the temperature rises, and the lattice expansion leads to the decrease of the refractive index. The phase change amount of the transmission light is linearly related to the voltage value, and the calibrated transmission light is transmitted to the polarization beam splitter 3 through the original light path in reverse.

[0110] The free spectral range of the fiber cavity used in the link is 1GHz-500GHz, and the fiber is a few-mode fiber. By continuously increasing the adjustable current source current, the polarization beam splitter 3 reflects the feedback light to the semiconductor laser 2, and injects the laser into the resonant cavity. When the phase of the feedback light matches the phase of the laser resonant, a self-consistent oscillation is formed in the cavity, and the wavelength of the laser is forced to lock to the fiber cavity resonance peak, until a spectrum as shown in Figure 3 is observed on the optical spectrum analyzer 7, wherein the soliton optical frequency comb 1 is a first soliton optical frequency comb, and at this time, the current is kept constant.

[0111] The collection process of the first soliton optical frequency comb is the same, and a second soliton optical frequency comb is generated in the second soliton microcomb generation and control module at the same time, and the spectrum is as shown in Figure 4 .

[0112] By directly turning off the current source signal and then turning it on again, the soliton optical frequency comb can be observed when it is connected to the photodetector as shown in Figure 5 , Figure 6 . Specifically, the transmission light signal is outputted from the transmission end of the fiber cavity, and contains the interference characteristics of the pump light and the resonant mode. The first adjustable current source 1 provides adjustable driving current to the semiconductor laser 2, and controls the pump light power by adjusting the current value, so that the system works in the soliton generation threshold interval. Referring again to Figure 5 , the self-injection locking key-on mechanism is realized through a transmission light feedback loop: the transmission light signal is reversely injected into the semiconductor laser 2 after phase adjustment by the silicon wafer 10, forcing the laser frequency to lock to the fiber cavity resonant mode, thereby realizing the self-starting of the key-on.

[0113] In some embodiments, the function of the photodetector 8 is to convert the transmission light signal of the fiber cavity 4 into an electrical signal, detect the transmission light power intensity, and trigger the second optical spectrum analyzer 9 to start analysis when the soliton generation threshold is reached. The second optical spectrum analyzer 9 is used to analyze the frequency spectrum characteristics of the electrical signal outputted by the photodetector 8, detect the equally spaced comb teeth distribution in the frequency spectrum, and determine the soliton state generation condition.

[0114] For the convenience of description, in the embodiment, the two-path soliton light frequency comb includes a first soliton light frequency comb and a second soliton light frequency comb, and when the two-path soliton light frequency comb is stable, the two-path soliton light frequency comb is connected to the distance measurement module, the gas spectrum analysis module and the communication module through the beam splitter 6.

[0115] The structure of the second soliton microcomb generation and control module is symmetrical to the first module, and the second soliton microcomb generation and control module includes a second optical fiber cavity and a second adjustable current source. The free spectral range of the second optical fiber cavity can be independently adjusted, and a preset frequency interval difference (for example, 1-500 GHz) is formed with the first optical fiber cavity 4. The two modules are physically isolated to avoid optical path crosstalk, and stable output of the two-path soliton state is realized through synchronous current control.

[0116] The distance measurement module is configured to receive the first soliton light frequency comb and the second soliton light frequency comb, generate a first interference signal through a reflection light path, and perform distance measurement through the first interference signal to output distance measurement data. The distance measurement module receives the two-path light frequency comb signal and generates the first interference signal based on a double comb interference principle.

[0117] As shown in FIG. 1, Figure 7 in some embodiments, the distance measurement module includes:

[0118] The first coupler 12 is configured to split the first soliton light frequency comb into a probe light beam and a reference light. The first coupler 12 is a fiber fusion taper type beam splitter, receives the first soliton light frequency comb input light beam, and splits the first soliton light frequency comb input light beam into two output light beams through an internal coupling area according to an energy ratio. One of the two output light beams is used as the probe light beam, and the other is used as the reference light beam.

[0119] The circulator 13 includes a first port, a second port and a third port. The first port is connected to the probe light beam. The second port is connected to the collimator 14, which is configured to direct the light beam to transmit to the free space. The collimator 14 is configured to direct the probe light beam to the surface of the target object 15 through the collimator 14, and receive the reflected light beam through a coaxial path. The third port is configured to send the reflected light beam to the second coupler 16 to receive the light signal returned from the target object. The circulator 13 realizes unidirectional transmission of the light path through the Faraday spin magnetic effect, and ensures that the incident light and the reflected light are physically isolated.

[0120] The collimator 14 receives the probe light beam output from the second port of the circulator 13, converts the divergent fiber output light into a parallel light beam to irradiate the surface of the target object, and receives the reflected light from the object through the same optical aperture. The front surface of the collimator 14 is coated with an anti-reflection film to reduce the echo loss, and the internal optical path design ensures the coaxial transmission and reception.

[0121] The second coupler 16 is used to combine the reference light beam and the reflected light beam to output a combined light signal, two input ports of the second coupler 16 respectively receive the reference light beam output by the first coupler 12 and the reflected light beam returned by the third port of the circulator 13, and light field superposition is realized through a gradient index lens.

[0122] The first polarization controller 17 and the second polarization controller 18 are both extruded fiber polarization adjusters, the birefringence characteristics of the polarization maintaining fiber are changed through mechanical pressure, and the polarization states of the first soliton light frequency comb and the second soliton light frequency comb are respectively optimized, and the linearly polarized light after adjustment can improve the contrast of subsequent interference fringes and suppress signal attenuation caused by polarization.

[0123] The third coupler 19 is a fiber coupler, two input ports of the third coupler 19 receive the combined light signal output by the second coupler 16 and the second soliton light frequency comb light source, three light paths are mixed through the principle of multimode interference, and the output light field contains the coherent superposition of reference light, reflected light and local oscillator light, forming an interference pattern carrying distance information.

[0124] The photosensitive surface of the first photodetector 20 receives the interference light field output by the third coupler 19, and converts the change of light intensity into a time-domain electric signal. The photodetector is built-in with a transimpedance amplifier, the output voltage signal amplitude is in a proportional relationship with the interference light intensity, and the output electric signal frequency reflects the target distance change rate.

[0125] The first oscilloscope 21 is a high-speed data acquisition device, the analog input end is connected to the output end of the photodetector, the time-domain waveform of the beat frequency electric signal is captured through an analog-to-digital converter, and the collected data is transmitted to a processing module through a bus for distance calculation.

[0126] In the distance measurement module, the first soliton light frequency comb and the second soliton light frequency comb are respectively connected to the first polarization controller 17 and the second polarization controller 18, part of the light of the first soliton light frequency comb is connected to the circulator 13 through the first coupler 12, and then is incident on the object surface through the collimator 14, at this time, the reflected light is received through the same collimator 14. The light of the first soliton light frequency comb which does not pass through the collimator 14, the reflected light of the first soliton light frequency comb passing through the object and the light of the second soliton light frequency comb are jointly connected to the same coupler, i.e. the third coupler 19, and then are incident on the first photodetector 20, and the interference signal is detected and data is collected through the first oscilloscope 21.

[0127] Specifically, the first soliton optical frequency comb enters the first coupler 12 and is split into two beams, wherein the probe beam enters the transmission channel through the first port of the circulator 13 and is transmitted to the collimator 14 through the second port. The collimator 14 converts the spherical wave transmitted by the optical fiber into a parallel light beam, which irradiates the surface of the target object at a specific incident angle. The reflected light of the object is coaxially received by the collimator 14, focused and returned through the second port of the circulator 13, and then output to the second coupler 16 through the third port. This coaxial light path eliminates the parallax error of the traditional split transceiver structure, ensuring the accuracy of long-distance measurement.

[0128] The reference beam is directly transmitted to the input end of the second coupler 16 through the first coupler 12. Inside the second coupler 16, the reflected beam output by the third port of the circulator 13 interferes with the reference beam for the first time. The two beams are derived from the same light source and carry the same frequency noise characteristics, and the interference result eliminates the phase noise of the light source itself. The combined light signal contains the phase delay information introduced by the object reflection.

[0129] The second polarization controller 18 adjusts the second soliton optical frequency comb to a linear polarization state and inputs it into the third coupler 19 as the local oscillator end. The third coupler 19 mixes the combined light signal with the second soliton optical frequency comb to generate a heterodyne interference field. The three-beam mixing design generates a beat signal with a carrier frequency of |Δf1-Δf2|, where Δf1 and Δf2 are the repetition frequency differences of the double soliton optical frequency combs. The photodetector converts the interference light intensity into an electrical domain beat signal, and the instantaneous frequency of the beat signal is proportional to the target distance change rate. The first oscilloscope 21 captures the time-domain waveform at a sampling rate of more than twice the highest beat frequency, and records the signal transmission to the processing module.

[0130] The soliton microcomb has stable output frequency and uniform interval, which effectively avoids the ranging error caused by wavelength instability in traditional laser interferometers, and has higher accuracy and robustness.

[0131] The gas spectrum analysis module is configured to receive the first soliton optical frequency comb and the second soliton optical frequency comb, generate a second interference signal using the gas cell 28, perform gas absorption spectrum analysis based on the second interference signal, and output gas spectrum analysis data.

[0132] In the gas spectrum analysis module, the first soliton optical frequency comb and the second soliton optical frequency comb are respectively connected to the third polarization controller 22 and the fourth polarization controller 26. Part of the light of the second soliton optical frequency comb is coupled into the gas cell 28, and the light emitted by the gas cell 28 is coupled into the second photodetector 25 together with part of the light of the first soliton optical frequency comb. Another part of the light of the first soliton optical frequency comb and another part of the light of the second soliton optical frequency comb are coupled into the third photodetector 30, and the two electrical signals are jointly input into the second oscilloscope 31 for signal detection and acquisition.

[0133] As Figure 8As shown, in some embodiments, the gas spectrum analysis module comprises:

[0134] The third polarization controller 22 and the fourth polarization controller 26 adopt a fiber extrusion adjustment structure, and perform polarization state optimization on the input first soliton optical frequency comb and the second soliton optical frequency comb respectively. The birefringence characteristics of the polarization maintaining fiber are changed by mechanical pressure, so that the output light maintains a stable linear polarization state. Polarization matching can improve the subsequent interference efficiency and avoid signal contrast attenuation.

[0135] The fourth coupler 23 is used for splitting the first soliton optical frequency comb into a first light beam and a second light beam, and the input end thereof is connected to the output end of the third polarization controller 22. The first soliton optical frequency comb is split into two independent transmission first light beams and second light beams according to the energy ratio.

[0136] The sixth coupler 27 is used for splitting the second soliton optical frequency comb into a third light beam and a fourth light beam. The sixth coupler 27 is symmetrical with the fourth coupler 23 in structure, and the input end thereof is connected to the output end of the fourth polarization controller 26. The second soliton optical frequency comb is split into a third light beam and a fourth light beam. The fourth light beam is allocated with higher power to enhance the signal strength of the absorption path.

[0137] The fifth coupler 24 is used for combining the first light beam and the third light beam to output a first combined light beam. The two input ends respectively receive the first light beam output by the fourth coupler 23 and the third light beam output by the sixth coupler 27. The light field superposition is realized through a graded refractive index lens, and the first combined light beam carrying reference interference information is output after the beam combination.

[0138] The gas cell 28 is used for performing gas molecule absorption on the fourth light beam to output an absorption signal. The gas cell 28 is a sealed quartz sample cavity, and antireflection window sheets are fused at both ends. The fourth light beam is vertically incident on the window sheet and penetrates through the gas medium to be measured. The gas molecules selectively absorb specific wavelengths, so that the spectrum of the output absorption signal carries a characteristic attenuation peak.

[0139] The seventh coupler 29 is used for combining the second light beam and the absorption signal to output a second combined light beam. The seventh coupler 29 is consistent with the fifth coupler 24 in structure. The input ends thereof respectively receive the second light beam output by the fourth coupler 23 and the absorption signal emitted by the gas cell 28, so as to realize the interference mixing of the incident light containing the gas absorption characteristics and the pure reference light, and output the second combined light beam.

[0140] The second photodetector 25 is used for receiving the first combined light beam and converting it into a first electric signal. The first electric signal represents a reference state.

[0141] The third photodetector 30 is configured to receive the second light beam and the second combined light beam and convert the second light beam and the second combined light beam into a second electrical signal. The second electrical signal carries gas absorption information.

[0142] The second oscilloscope 31 is configured to collect the first electrical signal and the second electrical signal to output gas spectrum analysis data. The first oscilloscope 21 and the second oscilloscope 31 are the same, and two analog input channels are connected to the output ends of the second photodetector 30 and the third photodetector 30 respectively to synchronously collect double-channel electrical signal waveforms. The collected data is transmitted to a processing module through a bus to perform spectrum comparison analysis.

[0143] Specifically, the first soliton optical frequency comb is adjusted to a linear polarization state by the third polarization controller 22 and input into the fourth coupler 23 to be split into two beams. The first light beam is directly mixed with the third light beam through the fifth coupler 24; the second light beam is transmitted to the seventh coupler 29 for standby. The second soliton optical frequency comb is optimized in polarization state by the fourth polarization controller 26 and input into the sixth coupler 27 to be split. The third light beam and the first light beam interfere with each other at the fifth coupler 24, and the first electrical signal is output by the second photodetector 25.

[0144] The fourth light beam is perpendicularly incident on the quartz window of the gas cell 28, and when the light beam penetrates the gas medium filled with methane, the gas molecules selectively absorb at specific wavelengths, resulting in a decrease in the corresponding spectral intensity. After the absorption signal is emitted through the window, the second light beam and the second combined light beam interfere with each other at the seventh coupler 29, so that the second combined light beam carries the double information of the gas absorption characteristics and the light source noise.

[0145] The third photodetector 30 converts the second combined light beam into the second electrical signal. The second oscilloscope 31 synchronously collects double-channel electrical signals to obtain time-domain voltage waveform data. In the time-domain signal, the first electrical signal reflects the reference state without gas interference, and the second electrical signal contains the gas absorption modulation effect.

[0146] In some embodiments, the second oscilloscope 31 is configured to collect the first electrical signal and the second electrical signal, extract frequency difference information by Fourier transform or spectrum analysis, and the frequency difference information is gas spectrum analysis data.

[0147] The Fourier transform performs discrete Fourier transform operation on the collected time-domain signal to convert the time sequence signal into frequency-domain spectral distribution. The transformation process is realized by fast Fourier transform algorithm, and the number of calculation points is set to an integer multiple of the signal period to suppress spectral leakage. The spectrum analysis adopts a short-time Fourier transform method, which intercepts a local signal segment through a sliding time window and extracts frequency-domain features in segments.

[0148] The frequency difference information is a quantitative value of the intensity difference of the double-channel electrical signal at the characteristic frequency point, which is caused by the intensity attenuation of the light at the specific wavelength due to gas absorption and is represented by a set of position and depth characteristic values of the concave peaks in the absorption spectrum.

[0149] In the process of Fourier transform, the second oscilloscope 31 receives the first electrical signal from the fifth coupler 24 and the second electrical signal from the seventh coupler 29 to capture continuous time-domain waveforms at a preset sampling rate, intercept time series of complete signal periods, perform fast Fourier transform calculation, and convert time-domain voltage value series into frequency-domain power spectral density distribution. The first electrical signal power spectrum reflects the reference spectral characteristics without gas interference, and the second electrical signal power spectrum shows the intensity attenuation of the 1650 nanometer frequency point caused by methane absorption, and the frequency difference information is regenerated again.

[0150] In the process of spectral analysis, the same input signal, i.e., the first electrical signal from the fifth coupler 24 and the second electrical signal from the seventh coupler 29, is processed by time-sharing sliding window, for example, a 200 nanosecond wide time window is set, and the window is slid along the signal time axis at a 50% overlap rate, the short-time Fourier transform is calculated independently in each window to generate the frequency spectrum distribution in the local time period, and at the 1650 nanometer characteristic frequency point, the attenuation coefficient change rate of the second electrical signal relative to the first electrical signal in different time segments is recorded, the instantaneous absorption characteristics caused by gas concentration fluctuation can be extracted, and a dynamic frequency difference information sequence with time resolution is output.

[0151] Due to the extremely high frequency stability of the soliton microcomb and the clear position of each comb tooth, the system has extremely high spectral resolution and measurement sensitivity, and is suitable for application scenarios such as gas concentration detection, environmental monitoring, and gas leakage warning.

[0152] The communication module is configured to transmit the first soliton optical frequency comb and the second soliton optical frequency comb through terahertz communication to generate a terahertz electromagnetic wave, and generate a modulation signal and a local oscillator signal for communication transmission based on the terahertz electromagnetic wave.

[0153] In the communication module, the first soliton optical frequency comb is firstly filtered by the first waveform shaper 32. One filtered wavelength is loaded with signal via the modulator 33, and the wavelength interval of the two wavelengths is 1-500 GHz. The modulated light and the other filtered light are accessed into the eighth coupler 34, pass through the 5 km optical fiber 35 and the UTC-PD1 (ultrafast photoelectric detector 1), i.e., the first photoelectric conversion unit 36 and the terahertz emission lens 37, and are received by the terahertz receiving lens 38 at the other end of the link. At the same time, the second soliton optical frequency comb is filtered by the second waveform shaper 42, and the wavelength interval of the two wavelengths is 1-500 GHz, which is 1-40 GHz away from the wavelength interval of the two wavelengths filtered by the first soliton optical frequency comb. The filtered light of the second soliton optical frequency comb is accessed into the terahertz amplifier 40 after passing through the UTC-PD, and is accessed into the fundamental frequency mixer 39 together with the signal received by the terahertz receiving lens 38. The mixed signal is accessed into the first spectrum analyzer 44 after passing through the electrical amplifier 43.

[0154] As shown in Figure 9 In some embodiments, the communication module comprises:

[0155] The first waveform shaper 32 is configured to perform filtering on the first soliton optical frequency comb to separate the first carrier wavelength and the first local oscillator wavelength. The first waveform shaper 32 is a programmable fiber grating filter, receives the first soliton optical frequency comb input light, adjusts the Bragg grating period through the thermo-optic effect, selectively reflects the target wavelength, and separates the first carrier wavelength and the first local oscillator wavelength with a fixed wavelength interval at the output end. The wavelength interval adjustment range covers 1-500 GHz.

[0156] The modulator 33 is configured to load the first carrier wavelength with communication data to generate loaded data. The optical input end is connected to the first carrier wavelength transmission optical fiber, the radio frequency port receives the communication data electrical signal, the waveguide refractive index is changed by the loading voltage, and the amplitude, phase or quadrature amplitude modulation of the optical carrier is realized.

[0157] The first coupler 12 is configured to combine the first carrier wavelength of the loaded data and the first local oscillator wavelength to output a dual-wavelength optical signal. The two input ends respectively receive the loaded data carrier wavelength output by the modulator 33 and the first local oscillator wavelength directly through the first waveform shaper 32. The coupler realizes non-interference combination of dual-wavelength in the internal tapered region, and outputs a dual-wavelength optical signal containing communication information and reference frequency.

[0158] A first photoelectric conversion unit 36 is configured to convert the dual-wavelength optical signal into a terahertz electromagnetic wave. The first photoelectric conversion unit 36 is a single-row carrier photodiode. The photosensitive surface receives the dual-wavelength optical signal. The photoelectric conversion unit 36 converts the light intensity change into a terahertz frequency band current oscillation by using the transit time effect of photo-generated carriers. The conversion efficiency is determined by the wavelength interval. The output electromagnetic wave frequency is equal to the difference between the two wavelengths.

[0159] A terahertz emission lens 37 is configured to radiate the terahertz electromagnetic wave. The terahertz emission lens 37 is a high-resistance silicon super surface lens. The front surface is coated with an anti-reflection film. The spherical wave output by the photodiode is collimated into a parallel beam. The lens curve compensates for wavefront distortion, forming a collimated terahertz beam for free space transmission.

[0160] A terahertz receiving lens 38 is configured to receive the terahertz electromagnetic wave transmitted in space. The terahertz receiving lens 38 is a condensing lens conjugated with the emission lens. The terahertz receiving lens 38 receives the electromagnetic wave transmitted in space and focuses the plane wave into the input end of the mixer through the gradient refractive index structure.

[0161] A second wave shaper 42 is configured to perform filtering processing on the second soliton optical frequency comb to separate the second carrier wavelength and the second local oscillator wavelength. The second wave shaper 42 is symmetrical to the first wave shaper 32. The second wave shaper 42 separates the second carrier wavelength and the second local oscillator wavelength with a wavelength interval of 1 to 500 GHz from the second soliton optical frequency comb. The wavelength interval is 1 to 40 GHz different from the first wavelength difference.

[0162] A second photoelectric conversion unit 41 is configured to convert the second carrier wavelength and the second local oscillator wavelength into a terahertz local oscillator reference signal. The second photoelectric conversion unit 41 respectively irradiates the second carrier wavelength and the second local oscillator wavelength to independent diodes. The second photoelectric conversion unit 41 generates a terahertz local oscillator reference signal corresponding to the wavelength interval through optical mixing effect.

[0163] A mixer is configured to mix and down-convert the signal output by the terahertz receiving lens 38 with the terahertz local oscillator reference signal to output a baseband signal. The signal port of the mixer is connected to the output end of the terahertz receiving lens 38. The local oscillator port receives the signal output by the second photoelectric conversion unit 41.

[0164] An electrical signal amplifier is configured to amplify the baseband signal. The input end of the electrical signal amplifier is connected to the intermediate frequency output end of the mixer. The electrical signal amplifier amplifies the weak baseband signal through a high electron mobility transistor.

[0165] A spectrum analyzer is configured to demodulate the amplified baseband signal and output a modulation signal and a local oscillator signal. The radio frequency input end of the spectrum analyzer receives the amplified baseband signal. The spectrum analyzer extracts the amplitude and phase information of the modulation signal through local oscillator scanning and quadrature demodulation.

[0166] Specifically, for the generation of the transmitting end signal, exemplarily, the first soliton optical comb enters the first waveform shaper 32, and the 1550.12 nanometer carrier wavelength and the 1550.52 nanometer local oscillator wavelength are separated out through the fiber grating reflection. The carrier wavelength is input into the modulator 33 to load the 16-QAM communication data, and the modulation depth is accurately controlled by the radio frequency driving voltage. After modulation, the carrier wavelength and the pure local oscillator wavelength are combined at the eighth coupler 34 to form a dual-wavelength composite optical signal. The signal is frequency-mixed by the first optoelectronic conversion unit 36 to generate a continuous terahertz wave with a frequency of 400 GHz. The terahertz transmitting lens 37 collimates the spherical wave into a parallel beam with a diameter of 5 cm, which is radiated in free space.

[0167] For signal demodulation of the receiving end, exemplarily, the terahertz receiving lens 38 captures the spatially transmitted electromagnetic wave and focuses it to the signal input port of the mixer. At the same time, the second soliton optical comb is input into the second waveform shaper 42 to separate out the 1550.08 nanometer and 1550.48 nanometer wavelength pairs. The second optoelectronic conversion unit 41 mixes the dual-wavelength light to generate a 402 GHz local oscillator reference signal, which is input into the local oscillator port of the mixer. The non-linear element inside the mixer generates the difference frequency component of the signal and the local oscillator, and outputs a baseband modulation signal with a center frequency of 2 GHz.

[0168] The electrical signal amplifier performs 40 decibel gain amplification on the microvolt-level baseband signal to compensate for the spatial transmission loss. The first spectrum analyzer 44 performs quadrature demodulation on the amplified signal: the signal is shifted to the baseband through digital down-conversion, the carrier phase is recovered using the Costas loop, and finally the 16-QAM constellation diagram is reconstructed.

[0169] Using the broadband characteristics of the soliton microcomb, multiple subcarriers can be transmitted in parallel, greatly improving the communication rate, and the theoretical rate can reach the Tbps (TeraBits Per Second) level, which is suitable for future high-speed optical interconnection, inter-chip communication and other frontier fields.

[0170] The processing module is configured to receive the distance measurement data to output a distance measurement result, receive the gas spectrum analysis data to output a gas spectrum analysis result, and receive the modulation signal and the local oscillator signal to output a modulation result.

[0171] In some embodiments, the processing module comprises:

[0172] The first processing module is configured to receive the distance measurement data, output a distance measurement result through a ranging inversion algorithm, specifically, receive the frequency-mixed electrical signal data stream transmitted by the distance measurement module, perform signal transformation and parameter calculation through a built-in algorithm, realize distance inversion based on the physical mapping relationship between the optical interference phase difference and the distance, and output the spatial position information of the target object.

[0173] The second processing module is configured to receive the gas spectrum analysis data, output a gas spectrum analysis result through a spectrum recognition algorithm, specifically, receive a frequency difference information matrix transmitted by the gas spectrum analysis module, identify a characteristic absorption peak through a spectrum line matching algorithm, integrate a standard molecular absorption database, correlate measured data and database features by using an optimization fitting algorithm, and output a gas type identification and a concentration quantitative value.

[0174] The third processing module is configured to receive a modulated modulated signal and a local oscillator signal, demodulate the modulated signal through a communication algorithm to output a modulation result, and the modulation result at least includes a bit error rate and a constellation diagram. The bit error rate is a statistical ratio of the number of error bits to the total number of transmission bits, and the constellation diagram is a coordinate distribution set of demodulated symbols on a complex plane. Specifically, the input end is connected to the output modulated signal and the local oscillator reference signal of the spectrum analyzer, and the original data stream is reconstructed through a quadrature demodulation architecture. The unit contains a carrier synchronization mechanism and a symbol decision logic, restores the transmission information through demapping processing, and outputs the communication quality evaluation parameters.

[0175] The processing module realizes a complete closed loop from bottom-layer hardware signal acquisition to upper-layer application result output, and guarantees efficient and stable operation of the entire multi-line multiplexing system.

[0176] For example, the temperature of the temperature control module is set to 25.8℃ to ensure that the optical cavity is in a stable thermal environment. Then, the output voltage of the voltage source 11 is set to 0.65V to adjust the output frequency and power of the semiconductor laser 2. The current source is turned on, and the current output is slowly increased. After adjusting to a suitable polarization state through the polarization beam splitter 3, the optical signal is coupled into a Fabry-Perot (F-P) cavity, i.e. a fiber cavity.

[0177] The F-P cavity is a two-mode fiber structure, and the two ends are coated with a Bragg reflection medium film with a reflectivity greater than 99.99%. The free spectral range (FSR) of the F-P cavity is adjustable in the range of 1GHz-500GHz, and the F-P cavity has a wide range of frequency control capability. The cavity output signal is amplified to 20dBm by the fiber amplifier 5 and then enters the 1:99 coupler. The output signal with an output ratio of 1% is connected to the spectrometer 7 for real-time monitoring.

[0178] In this experiment, the frequency interval of the first soliton optical frequency comb is set to 19.997GHz. By gradually increasing the current of the current source to 182.6mA, the first soliton optical frequency comb output is observed on the spectrometer 7, and the spectrum is as shown in Figure 3 The central wavelength is located at 1549.3nm. After that, the current is kept constant, and the temperature is maintained at 25.8℃ and the phase voltage is kept at 0.65V, realizing long-term stable output of the soliton optical frequency comb.

[0179] The second soliton microcomb generation and control module is configured in the same way to synchronously generate a second soliton optical frequency comb, whose frequency interval is set to 19.945 GHz, and the corresponding spectrum is as shown in Figure 4 The lower part is shown.

[0180] To verify the self-starting performance of the system, the first soliton microcomb generation and control module and the second soliton microcomb generation and control module are tested. The specific operation steps are: turn off the current source, and then turn it on again after 20 seconds, and connect the first soliton optical frequency comb output signal to the optical spectrum analyzer 7 to observe the soliton restart process. The experimental results show that after each restart, a single soliton spectrum output can be stably reproduced. After 5 start-stop cycles, the corresponding frequency evolution of the system is as shown in Figure 6 , which shows that the system has good self-starting performance and frequency reproducibility.

[0181] In this embodiment, by adjusting the current, voltage and polarization state of the semiconductor laser 2, two sets of soliton optical frequency combs with frequency intervals of 19.997 GHz and 19.945 GHz are stably output, providing a stable and reliable light source basis for subsequent ultrafast ranging, gas spectrum analysis and high-speed communication.

[0182] Among them, part of the first soliton optical frequency comb light passes through the first coupler 12 and is connected to the circulator 13, and then collimated by the collimator 14 and incident on the surface of the object to be measured. The object surface reflects the incident light, and the reflected light returns through the same collimator 14 and is guided out through the circulator 13, and is combined with the straight-through light of the first soliton optical frequency comb that has not passed through the reflection path and the output light signal of the second soliton optical frequency comb at the fiber coupler.

[0183] The combined interference signal is input to the first photodetector 20 to complete the photoelectric conversion, and the output electrical signal is connected to the 16 GHz bandwidth first oscilloscope 21 for high-bandwidth real-time sampling. The frequency difference of the two soliton optical frequency combs is set to 52 MHz, which can realize high-frequency resolution double-comb interference sampling.

[0184] During the ranging test, a continuous 5-time start-stop cycle operation is used to execute the key process of turning off the current source, waiting for 20 seconds, and then turning it on again for the first soliton optical frequency comb, in order to verify the stability of the interference signal and the reproducibility of the ranging after the system restarts. In the experiment, after each restart, the double-comb interference pattern can be stably observed on the oscilloscope, and the corresponding real-time data of the interference signal is as shown in Figure 10 .

[0185] The obtained interference signal data is processed by a computer, and the time domain signal is converted to the frequency domain by using the fast Fourier transform algorithm, and then the phase information of the interference beat frequency signal is extracted. According to the time-varying law of the interference phase, combined with the frequency interval difference (Δf = 52 MHz) of the soliton optical frequency comb in the system and the optical path change relationship, the distance information of the target object is calculated.

[0186] The experimental results show that the ranging system can complete a complete ranging process in 20 ns sampling time. After 20,000 cycles of data acquisition and statistical analysis, it is shown that the ranging accuracy is better than 20 microns. After multiple start-stop tests, the system frequency offset is small, and the ranging error is stable, which verifies that the system has fast response, high ranging accuracy and excellent self-starting characteristics.

[0187] On the basis of the first and second soliton optical frequency combs obtained by the first and second soliton comb generation and control modules, they are respectively connected to the third and fourth polarization controllers 22 and 26 to optimize the polarization state matching of the two optical signals and improve the interference signal-to-noise ratio. In the experiment, part of the second soliton optical frequency comb is coupled by the fiber coupler and then introduced into the hydrogen cyanide gas cell 28. The gas cell 28 is 48 cm long, the gas cell 28 has a pressure of 300 Torr, and the room temperature environment and stable gas flow state are maintained. The optical signal at the output end of the gas cell 28 and part of the first soliton optical frequency comb are combined by the second coupler 16 and then connected to the second photodetector 25. At the same time, the straight-through optical signals of the first and second soliton optical frequency combs that have not passed through the gas cell 28 are combined in the third coupler 19 and then connected to the third photodetector 30 as a reference signal. The two optical signals are synchronously connected to the 16 GHz bandwidth oscilloscope for real-time interference signal acquisition.

[0188] During the acquisition process, the same 5 start-stop cycle tests are also used to verify the influence of the soliton comb on the gas spectrum analysis performance after multiple restarts. After each restart, a clear interference pattern can be stably obtained, and the spectrum reproducibility is good.

[0189] The obtained interference signal is converted to the frequency domain by using the fast Fourier transform algorithm, and the double-comb interference spectrum before and after gas absorption is obtained. By comparing the amplitude difference between the reference signal and the signal after gas absorption, further mapping to the wavelength domain can obtain the absorption characteristic spectrum of the measured gas at a specific wavelength, as shown in Figure 11 , including the calculated gas absorption spectrum and the gas absorption curve in the database under the corresponding gas pressure and corresponding length.

[0190] The experimental results show that the system can complete a complete spectrum acquisition and analysis in 20 ns, and the wavelength corresponding to the characteristic absorption peak is consistent with the known absorption spectrum of hydrogen cyanide molecules. After multiple restart operations, the system has good reproducibility of the absorption characteristic peak, which verifies that the device has high sensitivity, fast response, excellent self-starting and reproducible gas detection capability.

[0191] The first soliton optical frequency comb output light first passes through the first waveform shaper 32, and the target wavelength (1550.30 nm, 1552.7 nm) is selected and filtered, and the wavelength interval of the two channels after filtering is set to 300 GHz. One of them (1550.30 nm) passes through the high-speed modulator 33 to load the high-speed data signal, and in this embodiment, two modulation formats of 16QAM and 64QAM are used.

[0192] The modulated signal and another unmodulated wavelength light (1552.7 nm) are combined by the eighth coupler 34, then transmitted through a 5km long single-mode fiber link, and converted to an electrical signal by the UTC-PD1, and the output frequency is in the terahertz band. The terahertz signal is radiated to the free space through the terahertz emission lens 37.

[0193] The receiving end is provided with a terahertz receiving lens 38, and the received terahertz signal is input to the subsequent demodulation link. At the same time, the second soliton optical frequency comb is filtered by the second waveform shaper 42 and outputs two light signals, and the wavelength interval (1550.4 nm, 1552.96 nm) is set to 320 GHz, which is input to the UTC-PD2 as a local oscillator signal, that is, the second optical-electric conversion unit 41 generates a corresponding terahertz local oscillator signal. The local oscillator signal is enhanced by the terahertz amplifier 40 and is input to the fundamental frequency mixer 39 together with the received signal to realize frequency down-conversion.

[0194] The mixed intermediate frequency signal is enhanced by the electric amplifier 43 and connected to the first spectrum analyzer 44 for constellation diagram observation and bit error rate test. The final output signal is demodulated by the computer, and the original modulation data is restored, and the performance of 16QAM and 64QAM modulation formats is evaluated, and the constellation diagram results are as shown in Figure 12

[0195] The experimental results show that in the terahertz carrier frequency range of 300GHz-600GHz, 240Gps high-speed data transmission can be realized, the bit error rate is better than 4.2×10 -2 , and the system can automatically restore the soliton output after 5 start-stop cycle tests, and the communication performance remains stable, with high speed, high signal-to-noise ratio, low delay and excellent self-starting characteristics.

[0196] ​The system provided by the application utilizes the self-injection locking effect to realize automatic mode locking of soliton microcomb start-up, simplifies user operation, and improves engineering applicability. Through reasonable light splitting and regulation, the soliton microcomb output realizes three major functions of ranging, spectrum, and communication in one system, significantly improving equipment utilization and economy. The system uses fiber connection, is small in size, is convenient to carry and deploy, and is suitable for field operation and mobile platforms. The soliton microcomb has advantages of low phase noise, wideband output, and frequency stability, so that the system is superior to traditional independent equipment in terms of measurement accuracy, spectral resolution, and communication rate. It can be applied to scientific research, industrial detection, environmental monitoring, optical communication, and other fields, and has good industrialization prospects.

[0197] Based on the above-mentioned soliton microcomb multi-line multiplexing system based on a key-on mechanism, some embodiments of the application provide a control method based on a soliton microcomb multi-line multiplexing system based on a key-on mechanism, comprising:

[0198] generating a first soliton optical frequency comb and a second soliton optical frequency comb;

[0199] based on the first soliton optical frequency comb and the second soliton optical frequency comb, performing distance measurement to output distance measurement data;

[0200] based on the first soliton optical frequency comb and the second soliton optical frequency comb, performing gas absorption spectrum analysis to output gas spectrum analysis data;

[0201] transmitting the first soliton optical frequency comb and the second soliton optical frequency comb through terahertz communication to generate modulation data;

[0202] outputting distance measurement results through the distance measurement data, outputting gas spectrum analysis results through the gas spectrum analysis data, and outputting modulation results through the modulation data.

[0203] In some embodiments, the generation of the first soliton optical frequency comb and the second soliton optical frequency comb comprises:

[0204] outputting a first soliton optical frequency comb with adjustable frequency interval under a self-injection locking key-on mechanism by a first soliton microcomb generating device;

[0205] outputting a second soliton optical frequency comb with adjustable frequency interval under a self-injection locking key-on mechanism by a second soliton microcomb generating device;

[0206] The generation process of the self-injection locking key-on mechanism comprises:

[0207] acquiring a transmitted light signal;

[0208] generating a self-injection locking key-on mechanism through the transmitted light signal.

[0209] It can be understood that the process of the method embodiment can refer to the system embodiment described above, and will not be described here.

[0210] The similar parts among the embodiments provided in the application can be referred to each other, and the specific embodiments provided above are only several examples under the general concept of the application, and do not constitute the limitation of the protection scope of the application. Any other embodiments extended according to the application scheme without creative labor for those skilled in the art shall fall within the protection scope of the application.

Claims

1. A multi-line multiplexing system based on a key-based soliton micro-comb, characterized in that: include: a first soliton microcomb generation and control module, comprising a first soliton microcomb generation device, a first optical fiber cavity, and a first adjustable current source, wherein the first optical fiber cavity is used to generate a transmitted light signal, and the first adjustable current source is used to receive the transmitted light signal to generate a self-injection locking keying mechanism, wherein the self-injection locking keying mechanism is used to trigger the first soliton microcomb generation device to output a first soliton optical frequency comb; a second soliton microcomb generation and control module, comprising a second soliton microcomb generation device, a second optical fiber cavity, and a second adjustable current source, wherein the second optical fiber cavity is used to generate a transmitted light signal, and the second adjustable current source is used to receive the transmitted light signal to generate a self-injection locking keying mechanism, wherein the self-injection locking keying mechanism is used to trigger the second soliton microcomb generation device to output a second soliton optical frequency comb; The first soliton optical frequency comb and the second soliton optical frequency comb are optical frequency combs with a frequency interval of a preset frequency interval; a distance measurement module, configured to receive the first soliton optical frequency comb and the second soliton optical frequency comb, generate a first interference signal through a reflection optical path, and perform distance measurement based on the first interference signal to output distance measurement data; a gas spectrum analysis module, configured to receive the first soliton optical frequency comb and the second soliton optical frequency comb, generate a second interference signal using a gas cell, perform gas absorption spectrum analysis using the second interference signal, and output gas spectrum analysis data; a communication module, configured to transmit the first soliton optical frequency comb and the second soliton optical frequency comb via terahertz communication to generate terahertz electromagnetic waves, and to generate a modulation signal and a local oscillation signal for communication transmission based on the terahertz electromagnetic waves; The processing module is configured to receive the distance measurement data to output a distance measurement result, receive the gas spectrum analysis data to output a gas spectrum analysis result, and receive the modulation signal and the local oscillation signal to output a modulation result.

2. The micro-comb multi-line multiplexing system based on a key-generating soliton is characterized in that: The first soliton micro-comb generation and control module further includes: Semiconductor lasers, used to generate pump light; The first adjustable current source is connected to the semiconductor laser and controls the output power of the pump light through the adjustable current to output the pump light of preset power; a polarization beam splitter, configured to couple the preset power pump light to the first soliton micro-comb generating device and receive the transmitted light of the pump light; a silicon chip, configured to receive the transmitted light and adjust the phase of the transmitted light to output adjusted transmitted light; a voltage source, the voltage source applying an adjustable voltage to the silicon wafer; a first soliton micro-comb generating device, configured to generate a first equally spaced frequency comb under the excitation of the preset power pump light; A spectrometer is used to detect the spectrum of the first equally spaced comb teeth. When the spectrometer detects the spectrum, the output parameters of the adjustable current source and voltage source are locked to generate a first soliton optical frequency comb.

3. The key-based soliton micro-comb multi-line multiplexing system according to claim 1, characterized in that: The distance measurement module includes: a first coupler, configured to split the first soliton optical frequency comb into a detection beam and a reference beam; A circulator, comprising a first port, a second port, and a third port, wherein the first port is connected to the detection beam, the second port is connected to a collimator, the collimator is used to direct the detection beam through the collimator to the surface of the detection object and receive the reflected beam through a coaxial path, and the third port sends the reflected beam to a second coupler; The second coupler is used to combine the reference beam and the reflected beam to output a combined optical signal; a first polarization controller, configured to adjust the polarization state of the first soliton optical frequency comb; a second polarization controller, configured to adjust the polarization state of the second soliton optical frequency comb; a third coupler, configured to perform optical field mixing on the combined optical signal and the second soliton optical frequency comb to output an interference optical field; a first photodetector, configured to convert the interference light field into a beat frequency electrical signal containing distance phase information; The first oscilloscope is used to collect the beat frequency electrical signal and output distance measurement data.

4. The key-based soliton micro-comb multi-line multiplexing system according to claim 1, characterized in that: The gas spectrum analysis module includes: a third polarization controller, configured to adjust the polarization state of the first soliton optical frequency comb; a fourth polarization controller, configured to adjust the polarization state of the second soliton optical frequency comb; a fourth coupler, configured to split the first soliton optical frequency comb into a first light beam and a second light beam; a sixth coupler, configured to split the second soliton optical frequency comb into a third light beam and a fourth light beam; a fifth coupler, configured to combine the first light beam and the third light beam to output a first combined light beam; a gas cell, configured to perform gas molecule absorption on the fourth light beam to output an absorption signal; a second photodetector, configured to receive the first combined light beam and convert the light into a first electrical signal; a seventh coupler, configured to combine the second light beam and the absorption signal to output a second combined light beam; a third photodetector, configured to receive the second light beam and the second combined light beam, and convert them into a second electrical signal; The second oscilloscope is used to collect the first electrical signal and the second electrical signal to output gas spectrum analysis data.

5. The micro-comb multi-line multiplexing system based on a key-generating soliton is characterized in that: The second oscilloscope is used to collect the first electrical signal and the second electrical signal, and extract frequency difference information through Fourier transform or spectrum analysis, where the frequency difference information is gas spectrum analysis data.

6. The key-based soliton micro-comb multi-line multiplexing system according to claim 1, characterized in that: The communication module includes: a first waveform shaper, configured to perform filtering processing on the first soliton optical frequency comb to separate a first carrier wavelength from a first local oscillator wavelength; a modulator, configured to load communication data onto the first carrier wavelength to generate loaded data; an eighth coupler, configured to combine the first carrier wavelength carrying the data and the first local oscillator wavelength to output a dual-wavelength optical signal; a first photoelectric conversion unit, configured to convert the dual-wavelength optical signal into a terahertz electromagnetic wave; A terahertz emission lens, used for radiating the terahertz electromagnetic wave; A terahertz receiving lens, used for receiving the terahertz electromagnetic wave transmitted through space; a second waveform shaper, configured to perform filtering processing on the second soliton optical frequency comb to separate a second carrier wavelength from a second local oscillator wavelength; a second photoelectric conversion unit, configured to convert the second carrier wavelength and the second local oscillator wavelength into a terahertz local oscillator reference signal; A mixer, configured to mix and down-convert the signal output by the terahertz receiving lens with the terahertz local oscillator reference signal to output a baseband signal; an electrical signal amplifier, configured to amplify the baseband signal; The first spectrum analyzer is used to demodulate the amplified baseband signal and output a modulation signal and a local oscillation signal.

7. The key-based soliton micro-comb multi-line multiplexing system according to claim 1, characterized in that: The processing module includes: A first processing module is configured to receive the distance measurement data and output a distance measurement result through a distance measurement inversion algorithm; a second processing module, configured to receive the gas spectrum analysis data and output a gas spectrum analysis result through a spectrum recognition algorithm; The third processing module is used to receive the modulated modulation signal and the local oscillator signal, and de-modulate the modulation signal through a communication algorithm to output a modulation result, where the modulation result at least includes a bit error rate and a constellation diagram.

8. The key-generating soliton micro-comb multi-line multiplexing system according to claim 1, characterized in that: The first optical fiber cavity and the second optical fiber cavity are two-mode optical fiber structures, and the free spectrum range is a preset range.

9. A control method based on a key-based soliton micro-comb multi-line multiplexing system, characterized in that: The key-generating soliton micro-comb multi-line multiplexing system according to any one of claims 1 to 8 comprises: generating a first soliton optical frequency comb and a second soliton optical frequency comb; performing distance measurement based on the first soliton optical frequency comb and the second soliton optical frequency comb to output distance measurement data; performing gas absorption spectrum analysis based on the first soliton optical frequency comb and the second soliton optical frequency comb to output gas spectrum analysis data; transmitting the first soliton optical frequency comb and the second soliton optical frequency comb via terahertz communication to generate modulated data; The distance measurement data is used to output a distance measurement result, the gas spectrum analysis data is used to output a gas spectrum analysis result, and the modulation data is used to output a modulation result.

10. The control method based on the key-generating soliton micro-comb multi-line multiplexing system according to claim 9, characterized in that: Generating the first soliton optical frequency comb and the second soliton optical frequency comb includes: The first soliton micro-comb generating device outputs a first soliton optical frequency comb with adjustable frequency interval under a self-injection locking key mechanism; The second soliton micro-comb generator outputs a second soliton optical frequency comb with adjustable frequency interval under the self-injection locking key mechanism; The generation process of the self-injection locking key mechanism includes: acquiring a transmitted light signal; A self-injection locking key mechanism is generated by the transmitted optical signal.

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