Spectrum detection system and spectrum detection method based on optical frequency comb

Abstract

The invention provides a spectrum detection system and a spectrum detection method based on an optical frequency comb. The spectrum detection system comprises a to-be-detected signal, a signal generation module, a frequency locking module, a frequency locking and frequency sweeping module and a frequency detection module. The input end of the frequency locking module and the input end of the frequency sweep locking module are respectively connected with the output end of the signal generation module, signals generated by the signal generation module are preprocessed through the frequency locking module and the frequency locking and frequency sweep module, and the preprocessed signals are sent to the frequency detection module; the signal to be detected, the output end of the frequency locking module and the output end of the frequency locking and frequency sweeping module are respectively connected with the input end of the frequency detection module, and the frequency detection module receives the signal to be detected and signals input by the frequency locking module and the frequency locking and frequency sweeping module and performs frequency spectrum detection.

Description

Technical Field

[0001] The present application relates to the field of spectrum detection technology, and in particular to a spectrum detection system and a spectrum detection method based on an optical frequency comb. Background Art

[0002] As modern communications, radars, and electronic warfare systems continue to develop in the direction of high speed and wide bandwidth, effectively intercepting and identifying enemy electronic signals is of great significance for electronic reconnaissance and intelligence support. The electromagnetic environment contains signals with multiple modes, different advantages and disadvantages, and complex spectrum distribution, which puts higher requirements on the receiver's receiving bandwidth, spectrum resolution, and real-time processing speed. In the process of microwave signal recognition, the radar's remote antenna is sometimes required to receive signals miles away from the central station. When the frequency of the radio frequency (RF) signal received by the antenna is unknown, the key is to first detect the signal frequency, then transmit a high-frequency RF signal (tens of GHz) from the remote end to the local site, and then convert it into a lower-frequency intermediate frequency (hundreds of MHz) signal.

[0003] However, the current detection of signal frequency has problems such as large measurement errors, high detector requirements, and high measurement costs. Summary of the invention

[0004] In view of this, the purpose of the present application is to propose a spectrum detection system and a spectrum detection method based on an optical frequency comb.

[0005] Based on the above purpose, the present application provides a spectrum detection system, including: a signal to be measured, a signal generation module, a frequency locking module, a frequency locking and frequency scanning module and a frequency detection module;

[0006] The input ends of the frequency locking module and the frequency locking and sweeping module are respectively connected to the output end of the signal generating module, and the signal output by the signal generating module is preprocessed by the frequency locking module and the frequency locking and sweeping module, and the preprocessed signal is sent to the frequency detection module;

[0007] The signal to be measured and the output ends of the frequency locking module and the frequency locking and frequency scanning module are respectively connected to the input end of the frequency detection module. The frequency detection module receives the signal to be measured and the signals input by the frequency locking module and the frequency locking and frequency scanning module, and performs spectrum detection.

[0008] Optionally, the signal generation module includes a first laser, a second laser, an optical frequency comb, a first optical coupler, and a second optical coupler;

[0009] The input end of the first optical coupler is connected to the output ends of the first laser and the optical frequency comb, couples the output signals of the first laser and the optical frequency comb, and sends the coupled signals to the frequency locking module via the output end;

[0010] The input end of the second optical coupler is connected to the output ends of the second laser and the optical frequency comb, couples the output signals of the second laser and the optical frequency comb, and sends the coupled signals to the frequency locking and scanning module via the output end.

[0011] Optionally, the frequency locking module is used to lock the frequency of the received signal and send the locking signal to the frequency detection module;

[0012] The frequency locking module includes a first input end, a second input end and a third input end, the first laser is connected to the first input end, the first optical coupler is connected to the second input end, and the optical frequency comb is connected to the third input end.

[0013] Optionally, the frequency locking and frequency sweeping module is used to perform frequency locking and frequency sweeping on the received signal;

[0014] The frequency locking and sweeping module includes a fourth input terminal, a fifth input terminal and a sixth input terminal, the optical frequency comb is connected to the fourth input terminal, the second optical coupler is connected to the fifth input terminal, and the second laser is connected to the sixth input terminal.

[0015] Optionally, the frequency locking module includes a first output end and a second output end, the first output end is connected to the first laser, and the second output end is connected to the frequency detection module;

[0016] The frequency locking and frequency sweeping module comprises a third output end and a fourth output end, the third output end is connected to the second laser, and the fourth output end is connected to the frequency detection module.

[0017] Optionally, the lock-sweep frequency module includes: an intensity modulator, a third optical coupler, a first photodetector, a power amplifier, a first bandpass filter, a first root mean square detector, an analog-to-digital converter and a first microcontroller unit;

[0018] The intensity modulator, the third optical coupler, the first photodetector, the power amplifier, the first bandpass filter, the first root mean square detector, the analog-to-digital converter and the first micro control unit are connected end to end in sequence.

[0019] Optionally, the system comprises:

[0020] The frequency locking module and the signal to be measured are connected to the intensity modulator, and the frequency locking and frequency sweeping module is connected to the third optical coupler;

[0021] The intensity modulator is used to receive the signal to be measured and the locking signal output by the frequency locking module, modulate the signal to be measured and the locking signal, and send the modulated signal to be measured and the locking signal to the third optical coupler;

[0022] The third optical coupler receives the modulated signal to be measured and the locking signal, couples the modulated signal to be measured and the locking signal, and sends the coupled signal to the first photodetector;

[0023] The first photodetector receives the coupled signal and determines a beat frequency signal;

[0024] The power amplifier, the first bandpass filter and the first square root detector process the beat frequency signal in sequence, and perform analog-to-digital conversion on the processed beat frequency signal through the analog-to-digital converter;

[0025] The first micro-control unit performs frequency detection on the converted beat frequency signal.

[0026] Optionally, the frequency locking module includes a first analog control module and a first digital control module;

[0027] The first analog control module includes a second photodetector, a first analog phase-locked loop and a first acousto-optic modulator;

[0028] The first digital control module includes a third photodetector, a first low-pass filter, a first power divider, a second band-pass filter, a second root mean square detector and a second micro control unit. The first power divider is connected to the first analog phase-locked loop.

[0029] Optionally, the frequency locking and frequency sweeping module includes a second analog control module and a second digital control module;

[0030] The second analog control module includes an optical switch, a second acousto-optic modulator, a fourth optical coupler, a fourth photodetector and a second analog phase-locked loop;

[0031] The second digital control module includes a fifth photodetector, a second low-pass filter, a second power divider, a third band-pass filter, a third root mean square detector and a third micro control unit.

[0032] Based on the same inventive concept, an embodiment of the present application further provides a spectrum detection method based on an optical frequency comb, which is applied to a spectrum detection system based on an optical frequency comb. The spectrum detection system based on an optical frequency comb includes: a signal to be measured, a signal generation module, a frequency locking module, a frequency locking and frequency scanning module, and a frequency detection module;

[0033] The method comprises:

[0034] The frequency locking module and the frequency locking and frequency scanning module are used to preprocess the signal output by the signal generating module and send the preprocessed signal to the frequency detecting module;

[0035] The frequency detection module is used to receive the signal to be tested and the signal input by the frequency locking module and the frequency locking and frequency scanning module, and perform spectrum detection.

[0036] As can be seen from the above, the spectrum detection system based on optical frequency comb provided by the present application includes: a signal to be measured, a signal generating module, a frequency locking module, a frequency locking and frequency sweeping module and a frequency detection module; the input ends of the frequency locking module and the frequency sweeping module are respectively connected to the output end of the signal generating module, and the signal output by the signal generating module is preprocessed by the frequency locking module and the frequency locking and frequency sweeping module, and the preprocessed signal is sent to the frequency detection module; the signal to be measured and the output ends of the frequency locking module and the frequency locking and frequency sweeping module are respectively connected to the input end of the frequency detection module, and the frequency detection module receives the signal to be measured and the signal input by the frequency locking module and the frequency locking and frequency sweeping module to perform spectrum detection. Among them, the frequency locking and frequency sweeping module can realize the free switching between the frequency locking mode and the frequency sweeping mode, thereby effectively saving the equipment cost, and at the same time, the frequency locking module and the frequency sweeping module preprocess the signal generating module to effectively improve the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 A schematic diagram of the structure and principle of a spectrum detection system based on an optical frequency comb according to an embodiment of the present application;

[0039] Figure 2 A schematic diagram of a flow chart of a spectrum detection method based on an optical frequency comb according to an embodiment of the present application;

[0040] Figure 3 Schematic diagram of the execution flow of the spectrum detection method based on optical frequency comb according to an embodiment of the present application;

[0041] Figure 4 Schematic diagram of test results of spectrum detection and signal down-conversion based on optical frequency comb according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0043] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0044] In order to facilitate understanding of the technical solutions of the present disclosure, some technical terms involved in the present disclosure are introduced below.

[0045] Down conversion: Converting a high frequency signal to a low frequency signal.

[0046] Optical frequency comb: A laser technology that has a spectrum consisting of a series of frequency components that are evenly spaced and have a coherent and stable phase relationship. Uses: high-precision measurement, timing and ranging, spectroscopy and optical communications, scientific research and technological development.

[0047] Beat frequency: When two light wave signals with similar frequencies are mixed, a low-frequency RF signal will be generated. This RF signal is the beat frequency, which is equal to the absolute value of the difference between the frequencies of the two light wave signals.

[0048] Sideband: refers to the modulated signal, which generates a frequency band on both sides of the center carrier frequency, called the sideband, that is, the frequency band formed after the signal to be detected is modulated. The bandwidth of the sideband is determined by the bandwidth of the modulated signal used and the modulation method.

[0049] In order to make the technical solution of the present disclosure clearer and easier to understand, the spectrum detection system and spectrum detection method provided by the embodiment of the present disclosure are described in detail below in conjunction with the accompanying drawings. As described in the background technology section, as modern communications, radars, and electronic warfare systems continue to develop in the direction of high speed and wide bandwidth, effectively intercepting and identifying enemy electronic signals is of great significance for electronic reconnaissance and intelligence support. The electromagnetic environment contains signals of various modes, different advantages and disadvantages, and complex spectrum distribution, which puts higher requirements on the receiving bandwidth, spectrum resolution, and real-time processing speed of the receiver. In the process of microwave signal recognition, the remote antenna of the radar is sometimes required to receive signals that are miles away from the central station. When the frequency of the radio frequency (RF) signal received by the antenna is unknown, the key is to first detect the signal frequency, then transmit a high-frequency RF signal (tens of GHz) from the remote end to the local site, and then convert it into a lower-frequency intermediate frequency (hundreds of MHz) signal.

[0050] However, regarding spectrum detection technology, firstly, the wavelength drift of the signal generation module used in it will bring about irreversible measurement errors, thereby reducing the measurement accuracy. Secondly, it uses a beat frequency scanning method to obtain the frequency, which has high requirements on the detector and cannot achieve wide-band frequency measurement. As for optical down-conversion technology, the frequency of the RF signal and the local oscillator signal must be similar. When the frequency of the signal to be down-converted is high (tens of GHz or even hundreds of GHz), the frequency of the local oscillator signal source needs to be high enough, so a high microwave source frequency is required, which makes the system cost higher. As a result, this down-conversion technology is difficult to apply to high-frequency environments.

[0051] In view of this, embodiments of the present application provide a spectrum detection system and a spectrum detection method based on an optical frequency comb.

[0052] like Figure 1 As shown, the spectrum detection system based on optical frequency comb includes: a signal to be measured, a signal generation module, a frequency locking module, a frequency locking and frequency scanning module and a frequency detection module;

[0053] The input ends of the frequency locking module and the frequency locking and sweeping module are respectively connected to the output end of the signal generating module, and the signal output by the signal generating module is preprocessed by the frequency locking module and the frequency locking and sweeping module, and the preprocessed signal is sent to the frequency detection module;

[0054] The signal to be measured and the output ends of the frequency locking module and the frequency locking and frequency scanning module are respectively connected to the input end of the frequency detection module. The frequency detection module receives the signal to be measured and the signals input by the frequency locking module and the frequency locking and frequency scanning module, and performs spectrum detection.

[0055] In some optional implementations, the signal to be measured includes a light source part and an optical coupler. Figure 1 As shown, the light source part includes: a first laser (1), a second laser (3) and an optical frequency comb (2); the optical coupler includes: a first optical coupler (4) and a second optical coupler (5); the frequency detection module includes: an intensity modulator (9), a third optical coupler (10), a first light detector (11), a power amplifier (12), a first bandpass filter (13), a first root mean square detector (14), an analog-to-digital converter (15) and a first micro control unit (16).

[0056] The frequency locking module (6) comprises a second photodetector (17), a third photodetector (20), a low-pass filter (21), a band-pass filter (23), an analog phase-locked loop (18), a power divider (22), a root mean square detector (24), an acousto-optic modulator (19), a microcontroller unit (25), a first input terminal ①, a second input terminal ②, a third input terminal ③, a first output terminal ④, and a second output terminal ⑤.

[0057] The frequency locking and frequency sweeping module (7) comprises an optical switch (26), an optical coupler (27), a fourth photodetector (28), a fifth photodetector (31), a low-pass filter (32), a band-pass filter (34), an analog phase-locked loop (29), a power divider (33), a root mean square detector (35), an acousto-optic modulator (30), a microcontroller unit (36), and a fourth input terminal ③, a fifth input terminal ②, a sixth input terminal ①, a third output terminal ④, a fourth output terminal ⑤, and a fifth output terminal ⑥.

[0058] It should be noted that Figure 1Correspondingly, the first optical coupler (4) is the optical coupler 1, the second optical coupler (5) is the optical coupler 2, the third optical coupler (10) is the optical coupler 3, the fourth optical coupler (27) is the optical coupler, the first photodetector (11) is the photodetector 1, the second photodetector (17) is the photodetector 2, the third photodetector (20) is the photodetector 3, the fourth photodetector (28) is the photodetector 4, the fifth photodetector (31) is the photodetector 5, the first bandpass filter (21) is the bandpass filter 1, the second bandpass filter (32) is the bandpass filter 2, the third bandpass filter (34) is the bandpass filter 3, the first root mean square detector (14) is the root mean square detector 1, the second The root mean square detector (24) is the root mean square detector 2, the third root mean square detector (35) is the root mean square detector 3, the first micro control unit (16) is the micro control unit 1, the second micro control unit (25) is the micro control unit 2, the third micro control unit (36) is the micro control unit 3, the first analog phase locked loop (18) is the analog phase locked loop 1, the second analog phase locked loop (29) is the analog phase locked loop 2, the first acousto-optic modulator (19) is the acousto-optic modulator 1, the second acousto-optic modulator (30) is the acousto-optic modulator 2, the first low-pass filter (13) is the low-pass filter 1, the second low-pass filter (23) is the low-pass filter 2, the first power distributor (22) is the power distributor 1, and the second power distributor (33) is the power distributor 2.

[0059] In some optional embodiments, the combination of the filter and the RMS detector can be replaced by any frequency-to-voltage device; the microcontroller unit can be replaced by a chip with any digital processing function; the acousto-optic modulator can be replaced by a photoinduced frequency shifting device, such as an electro-optic modulator; the digital-analog hybrid frequency locking module can be replaced by a digital frequency locking module or an analog frequency locking module; the analog phase-locked loop can be replaced by a high-precision digital phase-locked loop.

[0060] In some optional embodiments, such as Figure 1As shown, the first laser (1) is divided into two output paths, one path is input to the input end ① of the frequency locking module (6), and the other path is input to the first optical coupler 1 (4). The optical frequency comb (2) is divided into four output paths, (counting from top to bottom) the first path is input to the first optical coupler 1 (4), the second path is input to the input end ③ of the frequency locking module (6), the third path is input to the input end ③ of the frequency locking and frequency sweeping module (7), and the fourth path is input to the optical coupler 2 (5). The second laser (3) is divided into two output paths, one path is input to the input end ① of the frequency locking and frequency sweeping module (7), and the other path is input to the optical coupler 2 (5). The output of the optical coupler 1 (4) is connected to the input end ② of the frequency locking module (6), the output end ④ (i.e., the fourth input end) of the frequency locking module (6) is connected to the first laser (1), and the output end ⑤ (i.e., the second output end) of the frequency locking module (6) and the signal to be measured (8) are connected to the input end of the intensity modulator (9). The output of the optical coupler 2 (5) is connected to the input terminal ② of the frequency locking and frequency sweeping module (7).

[0061] Furthermore, the output terminal ④ (i.e., the third output terminal) of the frequency locking and frequency sweeping module (7) is connected to the second laser (3), the output terminal ⑥ is connected to the micro control unit 1 (16), and the output terminal ⑤ (i.e., the fourth output terminal) and the output of the intensity modulator (9) are connected to the input terminal of the optical coupler 3 (10). The connection line between the output terminal ⑥ of the frequency locking and frequency sweeping module (7) and the micro control unit 1 (16) is used to indicate that when the frequency locking and frequency sweeping module (7) is in the frequency sweeping working state, the beat frequency signals (S1 and S2) detected by the root mean square detector 3 (35) and the root mean square detector 1 (14) can maintain synchronization, which is convenient for the subsequent detection of the sideband frequency.

[0062] In some embodiments, the connection between the output terminal ⑥ of the frequency locking and frequency sweeping module (7) and the micro control unit 1 (16) is a network cable capable of completing synchronous communication, not an actual connection, and therefore a dotted line is used for connection. The output terminal ⑥ is not connected to the input of the micro control unit (16), but is only a representation of a virtual connection.

[0063] In some optional embodiments, the output of the optical coupler 3 (10) is connected to the input of the photodetector 1 (11), and the output of the photodetector 1 (11) is connected to the input of the power amplifier (12). The output of the power amplifier (12) is connected to the input of the bandpass filter 1 (13), and the output of the bandpass filter 1 (13) is connected to the input of the root mean square detector 1 (14), and the output of the root mean square detector 1 (14) is connected to the input of the analog-to-digital converter (15), and the output of the analog-to-digital converter (15) is connected to the input of the micro control unit 1 (16).

[0064] In some optional embodiments, the internal assembly structure of the frequency locking module (6) is as follows: input ② is connected to the input of the photodetector 3 (20), the output of the photodetector 3 (20) is connected to the input of the low-pass filter 1 (21), and the output of the low-pass filter 1 (21) is connected to the input of the power divider 1 (22). The power divider 1 (22) is divided into two outputs, one output to the analog phase-locked loop 1 (18), and the other output to the bandpass filter 2 (23). The output of the bandpass filter 2 (23) is connected to the input of the root mean square detector 2 (24), the output of the root mean square detector 2 (24) is connected to the input of the micro control unit 2 (25), and the output of the micro control unit 2 (25) is connected to the output ④. Input ③ is connected to the input of the photodetector 2 (17), the output of the photodetector 2 (17) is connected to the input of the analog phase-locked loop 1 (18), the output of the analog phase-locked loop 1 (18) and the input ① of the frequency locking module (6) are connected to the input of the acousto-optic modulator 1 (19), and the output of the acousto-optic modulator 1 (19) is connected to the output terminal ⑤.

[0065] The internal assembly structure of the frequency locking and sweeping module (7) is as follows: input ② is connected to the input of the photodetector 5 (31), the output of the photodetector 5 (31) is connected to the input of the low-pass filter 2 (32), and the output of the low-pass filter 2 (32) is connected to the input of the power divider 2 (33). The power divider 2 (33) is divided into two outputs, one output to the analog phase-locked loop 2 (29), and the other output to the bandpass filter 3 (34). The output of the bandpass filter 3 (34) is connected to the input of the root mean square detector 3 (35), and the output of the root mean square detector 3 (35) is connected to the input of the micro control unit 3 (36). The output of the micro control unit 3 (36) is connected to the output ④ and the output ⑥ and fed back to the optical switch (26). Input ③ is connected to the input of the photodetector 4 (28), and the output of the photodetector 4 (28) is connected to the input of the analog phase-locked loop 2 (29). The input ① of the frequency locking and frequency sweeping module (7) is connected to the input of the optical switch (26), and the optical switch (26) is divided into two outputs, one output is connected to the input of the optical coupler 4 (27), and the other output and the output of the analog phase-locked loop 2 (29) are connected to the input of the acousto-optic modulator 2 (30). The output of the acousto-optic modulator 2 (30) is connected to the input of the optical coupler 4 (27), and the output of the optical coupler 4 (27) is connected to the output terminal ⑤. Among them, the frequency locking and frequency sweeping module can realize the free switching between the frequency locking mode and the frequency sweeping mode.

[0066] In some optional embodiments, the outputs of the first laser (1) and the optical frequency comb (2) are respectively input into the frequency locking module (6), and the outputs of the first laser (1) and the optical frequency comb (2) are also input into the frequency locking module (6) after being coupled (by the optical coupler 1), so that the signal frequency of the first laser (1) is locked on a certain optical mode of the optical frequency comb (2). In the digital control module of the frequency locking module (6), the coupling signal is detected by the photodetector 3 (20) and filtered by the low-pass filter 1 (21) to obtain a beat frequency signal, and the beat frequency signal is divided into two paths after passing through the power divider 1 (22), one of which is filtered by the bandpass filter 2 (23), and the error signal is extracted by the root mean square detector 2 (24). After being processed by the micro control unit 2 (25), the signal is fed back to the first laser (1) (through the output terminal ④ of the frequency locking module), so that the frequency of the first laser (1) is roughly locked with the optical frequency comb (2). After the other beat frequency signal enters the analog phase-locked loop 1 in the analog control module, it is modulated by the acousto-optic modulator 1 (19) and the signal input by the first laser (1), so as to achieve accurate locking of the first laser (1) and the optical frequency comb (2). The signal to be measured (8) and the (frequency locking module output terminal ⑤) are locked and modulated by the intensity modulator (9) and then input into the optical coupler 3 (10). Among them, the root mean square (RMS) detector and the filter realize the conversion of frequency domain distribution into time domain intensity distribution.

[0067] In some optional embodiments, the frequency locking and frequency sweeping module (7) has two modes: frequency locking and frequency sweeping, which are controlled by the optical switch (26). The selection of the channel by the optical switch (26) is controlled by the feedback signal of the microcontroller unit 3 (36). When the optical switch (26) selects the channel with the acousto-optic modulator 2 (30), the frequency locking and frequency sweeping module (7) switches to the frequency locking mode, and locks the second laser (3) with the optical frequency comb (2). When the optical switch (26) selects the channel without the acousto-optic modulator 2 (30), the frequency locking and frequency sweeping module (7) switches to the frequency sweeping mode.

[0068] In some optional embodiments, the output signal of the frequency locking and sweeping module (7) (via the output terminal ⑤ of the frequency locking and sweeping module) is input into the optical coupler 3 (10) to couple with the signal modulated by the intensity modulator (9), and then the beat frequency signal is obtained after passing through the photodetector 1 (11). The signal strength is detected by the power amplifier (12), the bandpass filter 1 (13) and the root mean square detector 1 (14), and then the signal is sent to the micro control unit 1 (16) through the analog-to-digital converter (15) to realize frequency detection.

[0069] As can be seen from the above, the spectrum detection system based on optical frequency comb provided by the present application includes: a signal to be measured, a signal generating module, a frequency locking module, a frequency locking and frequency sweeping module and a frequency detection module; the input ends of the frequency locking module and the frequency sweeping module are respectively connected to the output end of the signal generating module, and the signal output by the signal generating module is preprocessed by the frequency locking module and the frequency locking and frequency sweeping module, and the preprocessed signal is sent to the frequency detection module; the signal to be measured and the output ends of the frequency locking module and the frequency locking and frequency sweeping module are respectively connected to the input end of the frequency detection module, and the frequency detection module receives the signal to be measured and the signal input by the frequency locking module and the frequency locking and frequency sweeping module, and performs spectrum detection. Among them, the frequency locking and frequency sweeping module can realize the free switching between the frequency locking mode and the frequency sweeping mode, thereby effectively saving the equipment cost, and at the same time, the frequency locking module and the frequency sweeping module preprocess the signal generating module to effectively improve the detection accuracy. In addition, by using low-performance electronic devices and embedded processors, this system can effectively reduce system costs and achieve high-precision frequency measurement. The frequency measurement range that can be achieved can cover hundreds of GHz or even THz, and the stability of the down-converted signal is guaranteed.

[0070] Based on the same inventive concept, corresponding to any of the above-mentioned embodiment systems, the present application also provides a spectrum detection and down-conversion method.

[0071] refer to Figure 2 , the spectrum detection and down-conversion method is applied to a spectrum detection system, the spectrum detection system based on optical frequency comb comprises: a signal to be measured, a signal generation module, a frequency locking module, a frequency locking and frequency scanning module and a frequency detection module;

[0072] The method comprises:

[0073] The frequency locking module and the frequency locking and frequency scanning module are used to preprocess the signal output by the signal generating module and send the preprocessed signal to the frequency detecting module;

[0074] The frequency detection module is used to receive the signal to be tested and the signal input by the frequency locking module and the frequency locking and frequency scanning module, and perform spectrum detection.

[0075] In some optional implementations, based on the spectrum detection system spectrum detection method such as Figure 3As shown, it specifically includes: first defining the number of scanned spectrum sideband bits X, and the number of adjacent peak bits g1(X) and g2(X) on the left and right sides of the sideband X. By controlling the optical switch (26) and the second laser (3) to perform frequency scanning, the microcontroller unit 3 (36) and the microcontroller unit 1 (16) synchronously record the signals S1 and S2 detected by the root mean square detector when the second laser (3) beats the optical frequency comb (2), the first laser (1) and the second laser (3). (S1 and S2 correspond to the first laser and the second laser, respectively) Among them, the waveform of the signal S1 is as shown Figure 4 As shown by the blue line in the figure, the waveform of signal S2 is as follows Figure 4 As shown by the red line in the figure. Due to the effect of bandpass filter 1 (13), two symmetrical peaks g1(X) and g2(X) are scanned on both sides of the X-th signal sideband. For example: The first sideband scanned corresponds to Figure 4 Peak 1 and Peak 2 in ).

[0076] Therefore, when the RMS detector 1 (14) detects that the signal S2 reaches a peak value, it indicates that the second laser (3) has swept to the vicinity of the modulation signal sideband. At this time, the optical switch (26) switches to the frequency locking path to lock the second laser (3). The frequency of the second laser remains unchanged, and the frequency change of the second laser when scanning to the peak on the same side of the previous sideband and this sideband |f[g1(X)]-f[g1(X-1)]| or |f[g2(X)]-f[g2(X-1)]| is recorded. For example: Figure 4 The frequency difference between peak 1 and peak 3, or the frequency difference between peak 2 and peak 4, is shown. Since signal S1 is obtained synchronously with signal S2, and S1 is periodic, the frequency difference between adjacent peaks is fixed. Therefore, by comparing with signal S1, the frequency difference between the peaks on the same side of adjacent sidebands of signal S2 can be obtained). The beat frequency is then obtained by photodetector 1 (11), the number of bits X of the sideband is increased by 1, and it is determined whether all sidebands have been detected. If not, the above operation is repeated to detect the next sideband until the detection is completed, and the scanning frequency is recorded at this time. When all sidebands are detected, the frequency difference between adjacent sidebands can be obtained (the frequency difference is the average of the frequency difference between the peaks on the same side of the two sidebands, for example: the frequency difference between the first sideband scanned and the second sideband scanned is Figure 4 The average of the peak 1 and 3 frequency differences and the peak 2 and 4 frequency differences shown), where the calculation formula is as follows:

[0077] Δf(X,X-1)={|f[g1(X)]-f[g1(X-1)]|+|f[g2(X)]-f[g2(X-1)]|} / 2

[0078] Furthermore, the frequency difference between the sideband and the carrier can be calculated based on the position relationship of the sideband, and finally the modulated signal frequency to be measured is obtained. If the Xth sideband is to be down-converted, it is only necessary to move the final sweep frequency by F. final -F(X), turn on the frequency lock channel lock.

[0079] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied to a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the described method.

[0080] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0081] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0082] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present application difficult to understand, the known power supply / ground connection with the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. In addition, the device can be shown in the form of a block diagram to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform to be implemented in the embodiments of the present application (that is, these details should be fully within the scope of understanding of those skilled in the art). In the case of elaborating specific details (e.g., circuits) to describe exemplary embodiments of the present application, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details or when these specific details are changed. Therefore, these descriptions should be considered to be illustrative rather than restrictive.

[0083] Although the present application has been described in conjunction with specific embodiments of the present application, many replacements, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed.

[0084] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. A spectrum detection system based on optical frequency comb, It is characterized in that include: Signal to be tested, signal generation module, frequency locking module, frequency locking and frequency sweeping module and frequency detection module; The input ends of the frequency locking module and the frequency locking and sweeping module are respectively connected to the output end of the signal generating module, and the signal output by the signal generating module is preprocessed by the frequency locking module and the frequency locking and sweeping module, and the preprocessed signal is sent to the frequency detection module; The signal to be measured and the output ends of the frequency locking module and the frequency locking and frequency scanning module are respectively connected to the input end of the frequency detection module. The frequency detection module receives the signal to be measured and the signals input by the frequency locking module and the frequency locking and frequency scanning module, and performs spectrum detection.

2. The system according to claim 1, It is characterized in that The signal generation module includes a first laser, a second laser, an optical frequency comb, a first optical coupler, and a second optical coupler; The input end of the first optical coupler is connected to the output ends of the first laser and the optical frequency comb, couples the output signals of the first laser and the optical frequency comb, and sends the coupled signals to the frequency locking module via the output end; The input end of the second optical coupler is connected to the output ends of the second laser and the optical frequency comb, couples the output signals of the second laser and the optical frequency comb, and sends the coupled signals to the frequency locking and scanning module via the output end.

3. The system according to claim 2, It is characterized in that The frequency locking module is used to lock the frequency of the received signal and send the locking signal to the frequency detection module; The frequency locking module includes a first input end, a second input end and a third input end, the first laser is connected to the first input end, the first optical coupler is connected to the second input end, and the optical frequency comb is connected to the third input end.

4. The system according to claim 3, It is characterized in that The frequency locking and frequency sweeping module is used to perform frequency locking and frequency sweeping on the received signal; The frequency locking and sweeping module includes a fourth input terminal, a fifth input terminal and a sixth input terminal, the optical frequency comb is connected to the fourth input terminal, the second optical coupler is connected to the fifth input terminal, and the second laser is connected to the sixth input terminal.

5. The system according to claim 4, It is characterized in that The frequency locking module comprises a first output end and a second output end, the first output end is connected to the first laser, and the second output end is connected to the frequency detection module; The frequency locking and frequency sweeping module comprises a third output end and a fourth output end, the third output end is connected to the second laser, and the fourth output end is connected to the frequency detection module.

6. The system according to claim 1, It is characterized in that The frequency locking and frequency sweeping module comprises: an intensity modulator, a third optical coupler, a first photodetector, a power amplifier, a first bandpass filter, a first root mean square detector, an analog-to-digital converter and a first micro control unit; The intensity modulator, the third optical coupler, the first photodetector, the power amplifier, the first bandpass filter, the first root mean square detector, the analog-to-digital converter and the first micro control unit are connected end to end in sequence.

7. The system according to claim 6, It is characterized in that The system comprises: The frequency locking module and the signal to be measured are connected to the intensity modulator, and the frequency locking and frequency sweeping module is connected to the third optical coupler; The intensity modulator is used to receive the signal to be measured and the locking signal output by the frequency locking module, modulate the signal to be measured and the locking signal, and send the modulated signal to be measured and the locking signal to the third optical coupler; The third optical coupler receives the modulated signal to be measured and the locking signal, couples the modulated signal to be measured and the locking signal, and sends the coupled signal to the first photodetector; The first photodetector receives the coupled signal and determines a beat frequency signal; The power amplifier, the first bandpass filter and the first square root detector process the beat frequency signal in sequence, and perform analog-to-digital conversion on the processed beat frequency signal through the analog-to-digital converter; The first micro-control unit performs frequency detection on the converted beat frequency signal.

8. The system according to claim 1, It is characterized in that The frequency locking module includes a first analog control module and a first digital control module; The first analog control module includes a second photodetector, a first analog phase-locked loop and a first acousto-optic modulator; The first digital control module includes a third photodetector, a first low-pass filter, a first power divider, a second band-pass filter, a second root mean square detector and a second micro control unit.

9. The system according to claim 1, It is characterized in that The frequency locking and frequency sweeping module includes a second analog control module and a second digital control module; The second analog control module includes an optical switch, a second acousto-optic modulator, a fourth optical coupler, a fourth photodetector and a second analog phase-locked loop; The second digital control module includes a fifth photodetector, a second low-pass filter, a second power divider, a third band-pass filter, a third root mean square detector and a third micro control unit.

10. A spectrum detection method based on optical frequency comb, It is characterized in that Applied to a spectrum detection system, the spectrum detection system comprises: a signal to be measured, a signal generation module, a frequency locking module, a frequency locking and frequency scanning module and a frequency detection module; The method comprises: The frequency locking module and the frequency locking and frequency scanning module are used to preprocess the signal output by the signal generating module and send the preprocessed signal to the frequency detecting module; The frequency detection module is used to receive the signal to be tested and the signal input by the frequency locking module and the frequency locking and frequency scanning module, and perform spectrum detection.

Images