Method and system for multiplying number of carriers of cyclic frequency shift multi-carrier optical fiber light source

Abstract

The invention discloses a method and system for multiplying the number of carriers of a cyclic frequency shift multi-carrier optical fiber light source. The method comprises the following steps: generating an initial seed optical signal by adopting a laser light source; dividing the initial seed optical signal into two beams through a beam splitting coupler I, and performing frequency shift processing on the first beam of seed optical signal; carrying out delay processing on the second beam of seed optical signal, so that the second beam of seed optical signal is synchronized with the frequency-shifted optical signal; after the synchronized optical signals are coupled, double-sideband modulation is carried out; and the modulated optical signal is divided into an output signal and a feedback signal through a beam splitting coupler II, and the feedback signal is input into the beam splitting coupler I again for cyclic processing, so that iterative multiplication of the number of carriers is realized. Under the same number of cycles, the number of carriers is obviously higher than that of the traditional method; by reducing the number of cycles, noise accumulation can be effectively reduced, and the signal-to-noise ratio of the multi-carrier signal is improved; the output multi-carrier signal is wide in coverage spectrum range, is suitable for various application scenes, and can flexibly control the carrier quantity and the frequency interval.

Description

Technical Field

[0001] The present application belongs to the field of optical fiber communication and spectroscopy technology, and specifically relates to a method and system for multiplying the number of carriers in a cyclic frequency-shifted multi-carrier optical fiber light source, which is suitable for scenarios such as optical communication, optical fiber sensing, and microwave photonics that require high-density multi-carrier light sources. Background Art

[0002] Multi-carrier light sources possess a large number of optical frequency components with identical frequency intervals in the frequency domain and are widely used in fields such as fiber-optic communications, fiber-optic sensing, microwave photonics, optically controlled phased array radar, spectroscopy, and optical component testing. Traditional multi-carrier light sources are typically based on cyclic frequency shifting technology, which generates multi-carrier optical signals by constructing a cyclic frequency shifting loop. However, these traditional methods have the following problems:

[0003] Limited number of carriers: Although theoretically the number of carriers can be increased by increasing the number of cycles, in practice, noise accumulation deteriorates rapidly as the number of cycles increases, limiting the increase in the number of carriers.

[0004] Low signal-to-noise ratio: Multiple cycles cause the signal-to-noise ratio of the optical signal to drop significantly, affecting system performance.

[0005] Inefficiency: Traditional methods generate a limited number of carriers under the same number of cycles, making it difficult to meet high-density carrier requirements. Summary of the Invention

[0006] The purpose of this application is to provide a method and system for multiplying the number of carriers of a multi-carrier fiber light source that can realize cyclic frequency shifting, which realizes rapid multiplication of the number of carriers and effective suppression of noise by optimizing the optical path design and modulation method.

[0007] To solve at least one of the above technical problems, the technical solution adopted in this application is:

[0008] A method for multiplying the number of carriers of a cyclic frequency-shifted multi-carrier optical fiber light source, comprising:

[0009] A laser light source is used to generate an initial seed light signal;

[0010] The initial seed optical signal is split into two beams by a beam splitting coupler, and the first beam seed optical signal is subjected to frequency shift processing; the second beam seed optical signal is subjected to delay processing to synchronize it with the frequency-shifted optical signal;

[0011] The synchronized optical signals are coupled and then subjected to double-sideband modulation;

[0012] The modulated optical signal is split into an output signal and a feedback signal through a beam splitting coupler, and the feedback signal is re-input into the beam splitting coupler for cyclic processing to achieve iterative multiplication of the number of carriers.

[0013] Furthermore, the laser light source is a distributed feedback laser, and the initial seed light signal generated by the laser light source is a continuous wave light signal with a narrow linewidth and a frequency of f0.

[0014] Furthermore, the first seed light signal is processed by a single sideband modulator to generate a signal with a frequency shift of f m Frequency-shifted optical signal;

[0015] The second seed optical signal is processed through a time delay line; the delay amount of the time delay line can be dynamically adjusted according to the transmission time of the optical signal in the system.

[0016] Furthermore, the coupling of the synchronized optical signals and then performing double-sideband modulation includes:

[0017] A beam-combining coupler is used to synchronously couple the delayed light and the frequency-shifted light;

[0018] Then the coupled light is double-side-band modulated by an electro-optical modulator with a modulation frequency of nf m , where n is a positive integer greater than 1.

[0019] Furthermore, the first beam splitter coupler is a 2×2 optical coupler.

[0020] Furthermore, the single sideband modulator is composed of a frequency of f m The electro-optical modulator is driven by a radio frequency signal source 1 with a frequency of nf m The RF signal source 2 is driven, and n is a positive integer greater than 1;

[0021] Furthermore, the RF signal source 1 and the RF signal source 2 are both medium- and low-frequency RF signal sources.

[0022] Furthermore, the relationship between the number of cycles N and the number of newly generated carrier frequencies is:

[0023] When the number of cycles N≤n-1, the number of new carrier frequencies generated in each cycle is 4N+1, and the number of carrier frequencies output after N cycles is (N+1)×(2N+1);

[0024] When the number of cycles N>n-1, the number of new carrier frequencies generated in each cycle is 2n+1, and the number of carrier frequencies output after N cycles is N×(2n+1)+1.

[0025] A system for multiplying the number of carriers of a cyclic frequency-shifted multi-carrier optical fiber light source, comprising:

[0026] Distributed feedback lasers for generating narrow-linewidth continuous-wave seed light;

[0027] Beam splitting coupler 1, splits the seed light into two beams;

[0028] a single-sideband modulator connected to an output end of the first beam splitter coupler and performing frequency shift processing on the first seed light beam;

[0029] a time delay line connected to the other output end of the first beam splitter coupler, for performing delay processing on the second beam of seed light;

[0030] A beam-combining coupler is used to synchronously couple the delayed light with the frequency-shifted light;

[0031] Electro-optical modulator, which performs double-sideband modulation on the synchronously coupled light;

[0032] The second beam splitter coupler divides the modulated optical signal into an output end and a feedback end, and the feedback end is connected to the input end of the first beam splitter coupler to form a loop structure.

[0033] Furthermore, the single sideband modulator is composed of a frequency of f m The electro-optical modulator is driven by a radio frequency signal source 1 with a frequency of nf m The RF signal source 2 is driven, and n is a positive integer greater than 1;

[0034] The single cycle process of the cyclic structure includes: the light is frequency-shifted by the single sideband modulator to generate a frequency interval of f m The carrier wave is synchronously input into the electro-optical modulator for double-sideband modulation with the delayed seed light to generate a frequency interval of nf m New carrier.

[0035] The present application designs a method and system for multiplying the number of carriers in a cyclic frequency-shifted multi-carrier fiber light source. Under the same number of cycles, the number of carriers is significantly higher than that of traditional methods. By reducing the number of cycles, noise accumulation can be effectively reduced and the signal-to-noise ratio of the multi-carrier signal can be improved. Moreover, the output multi-carrier signal covers a wider spectral range and is suitable for a variety of application scenarios. By adjusting the RF signal frequency and the number of cycles, the number of carriers and the frequency interval can be flexibly controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the method for multiplying the number of carriers of a multi-carrier fiber light source in this application;

[0037] Figure 2 This is a schematic diagram of the structure of the transmission system for multi-carrier optical fiber light source with multiplied carrier number in this application;

[0038] Figure 3 Schematic diagram of the spectrum change when the number of cycles N=1 in this application;

[0039] Figure 4 It is a schematic diagram of the spectrum change when the number of cycles N=2 in this application. DETAILED DESCRIPTION

[0040] The existing design is to inject seed light into the single-sideband modulator in the cyclic frequency shift loop to generate a certain frequency shift amount, a part of which is output at the output end of the cyclic frequency shift loop, and the rest is circulated in the loop, and finally a multi-carrier output with the frequency shift amount as the frequency interval is obtained at the output end. The frequency interval of the multi-carrier is always equal to the frequency of the RF signal driving the modulator; the number of multi-carriers generated depends on the number of cycles of the multi-carrier in the loop. Although the method of generating a multi-carrier fiber light source based on cyclic frequency shift theoretically breaks through the limitation of the modulator bandwidth on the number of carriers, and the number of multi-carriers can be increased by increasing the number of cycles, the noise accumulation in the actual loop will increase rapidly with the increase in the number of cycles, resulting in a significant deterioration of the signal-to-noise ratio, which limits the number of multi-carriers that can be output in the end. Therefore, how to achieve rapid multiplication of the number of carriers and effective suppression of noise by optimizing the optical path design and modulation method is the focus of the invention of this application.

[0041] The purpose of this application is to provide a method and system for multiplying the number of carriers of a multi-carrier fiber light source that can achieve cyclic frequency shifting. The application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] This application provides a method for multiplying the number of carriers of a cyclic frequency shifted multi-carrier fiber light source. The transmission flow chart is as follows: Figure 1 As shown, accordingly, the loop structure diagram involved is as follows Figure 2 As shown, the steps include:

[0043] S1. Use a laser light source to generate an initial seed light signal.

[0044] The laser light source is a distributed feedback laser (DFB-LD), which generates an initial seed optical signal, and the initial seed optical signal is a continuous wave optical signal with a narrow linewidth and a frequency of f0.

[0045] S2. Split the initial seed optical signal into two beams through a beam splitting coupler (OC1), perform frequency shift processing on the first seed optical signal, and delay the second seed optical signal to synchronize it with the frequency-shifted optical signal.

[0046] The initial seed optical signal is input into the first beam splitting coupler (OC1), and the first beam splitting coupler (OC1) splits the initial seed optical signal into two beams, namely a first beam seed optical signal and a second beam seed optical signal.

[0047] The first seed light beam is modulated by a single sideband modulator (SSB) to generate a signal with a frequency shift of f m frequency-shifted optical signal.

[0048] The second seed optical signal is delayed through a time delay line (TDL), allowing the delayed optical signal to be synchronously coupled with the frequency-shifted optical signal via a beam-combining coupler (OC3). The TDL delay is set to synchronize the unshifted and frequency-shifted light at the input of the electro-optical modulator (EOM). The TDL delay is dynamically adjustable based on the optical signal's transmission time in the system to ensure strict synchronization between the two optical signals.

[0049] S3. Couple the synchronized optical signals and then perform double-sideband modulation.

[0050] Specifically, the delayed light and the frequency-shifted light are synchronously coupled by a beam-combining coupler (OC3); then the coupled light is double-side-band modulated by an electro-optical modulator (EOM) with a modulation frequency of nf m , where n is a positive integer greater than 1. The two optical signals are synchronously coupled and input into the electro-optical modulator (EOM) for double-sideband modulation to generate a frequency interval of nf m The new carrier of , n is a positive integer greater than 1.

[0051] In this embodiment, the first beam splitter coupler (OC1) is a 2×2 optical coupler.

[0052] Among them, the single sideband modulator (SSB) consists of a frequency of f m The electro-optical modulator (EOM) is driven by a radio frequency signal source 1 (RF1) with a frequency of nf m The RF signal source 1 (RF1) and the RF signal source 2 (RF2) are driven by the RF signal source 2 (RF2), and n is a positive integer greater than 1. Preferably, the RF signal source 1 (RF1) and the RF signal source 2 (RF2) are both medium and low frequency RF signal sources.

[0053] S4. Splitting the modulated optical signal into an output signal and a feedback signal through the second beam splitter coupler (OC2), and re-inputting the feedback signal into the first beam splitter coupler for cyclic processing to achieve iterative multiplication of the number of carriers.

[0054] The modulated optical signal is split into two beams by a second beam splitter coupler (OC2), which serve as a multi-carrier output signal and a multi-carrier feedback signal respectively.

[0055] The multi-carrier output signal is directly output from the output terminal; the multi-carrier feedback signal is re-input into the beam splitter coupler 1 (OC1) for cyclic processing. By controlling the number of loops N, the number of carriers is multiplied and output, and then the number of carriers is iteratively multiplied. Among them, the single cycle process includes: the light is frequency-shifted by the single sideband modulator (SSB) to generate a frequency interval of f mThe carrier wave is synchronously input into the electro-optical modulator (EOM) for double-sideband modulation with the delayed seed light to generate a frequency interval of nf m New carrier.

[0056] In this embodiment, the relationship between the number of cycles N and the number of newly generated carrier frequencies is:

[0057] When the number of cycles N≤n-1, the number of new carrier frequencies generated in each cycle is 4N+1, and the number of carrier frequencies output after N cycles is (N+1)×(2N+1);

[0058] When the number of cycles N>n-1, the number of new carrier frequencies generated in each cycle is 2n+1, and the number of carriers output after N cycles is N×(2n+1)+1; where n is a positive integer greater than 1.

[0059] like Figure 2 As shown, a distributed feedback laser (DFB-LD) is provided for generating initial seed light, and a first beam splitter coupler (OC1) is provided for splitting the light source signal of the initial seed light into two seed light beams. The two output ends of the first beam splitter coupler (OC1) are respectively connected to a time delay line (TDL) for delaying the output light and the input end of a cyclic structure for frequency multiplication. The output end of the time delay line (TDL) is connected to the output end of a single-sideband modulator (SSB) in the cyclic structure and to the input end of a beam combining coupler (OC3) for combining the two seed light beams into one. The output end of the beam combining coupler (OC3) is fed into an electro-optical modulator (EOM) in the cyclic structure to generate frequency multiplication. The frequency-multiplied multi-carrier optical signal enters the input end of the second beam splitter coupler (OC2), which is connected to the output end of the electro-optical modulator (EOM). One port of the second splitter coupler (OC2) outputs part of the multi-carrier optical signal, and the other output port is connected to the other input port of the first splitter coupler (OC1), and the remaining multi-carrier signal is re-input into the cyclic structure as seed light for a new round of frequency multiplication.

[0060] In this embodiment, the cyclic structure for generating frequency multiplication includes a first beam splitter coupler (OC1), a single sideband modulator (SSB), a beam combiner coupler (OC3), an electro-optical modulator (EOM), and a second beam splitter coupler (OC2). An input end of the first beam splitter coupler (OC1) is connected to an output end of the second beam splitter coupler (OC2), and the output end of the first beam splitter coupler (OC1) is connected to the input end of the single sideband modulator (SSB); the output end of the single sideband modulator (SSB) is connected to an input end of the beam combiner coupler (OC3), the output end of the beam combiner coupler (OC3) is connected to the input end of the electro-optical modulator (EOM), and the output end of the electro-optical modulator (EOM) is connected to the input end of the second beam splitter coupler (OC2).

[0061] The RF input of the single-sideband modulator (SSB) is connected to RF signal source 1 (RF1), and the RF input of the electro-optical modulator (EOM) is connected to RF signal source 2 (RF2). Both RF signal source 1 (RF1) and RF signal source 2 (RF2) are medium-low frequency RF signal sources. The frequency of RF signal source 1 (RF1) is f m , the frequency of RF signal source 2 (RF2) is nf m , n is a positive integer greater than 1.

[0062] In this embodiment, the initial seed light enters the frequency multiplication cycle structure through an output port of the splitting coupler 1 (OC1), and is first modulated by a single sideband modulator (SSB) to achieve a frequency shift of f in the frequency domain. m The initial seed light is input into the time delay line (TDL) through the other output port of the beam splitter coupler (OC1), and after the time delay, it is combined with the frequency shift of f m The frequency-shifted light is synchronized in time and sent together through a beam-combining coupler (OC3) to an electro-optical modulator (EOM) for double-sideband modulation. The EOM performs double-sideband modulation on the seed light and the frequency-shifted light to generate new carrier frequencies. A portion of each carrier frequency is output as the light source output via one output port of the second beam-splitting coupler (OC2), which is connected to the output of the EOM. The remaining portion is output via the other output port of the second beam-splitting coupler (OC2) and input as new seed light to the other input port of the first beam-splitting coupler (OC1). The aforementioned process is repeated, performing high-speed iterations to output multi-carrier optical signals, completing the cyclic multiplication of the number of carriers.

[0063] The present application proposes a method that can achieve a doubling of the number of multi-carriers under the same number of cyclic frequency shift cycles. This is because the cyclic structure proposed in the present application is used to synchronously couple the split seed light and the frequency-shifted light, and then undergo double-sideband modulation with a frequency shift of n times. Compared with the existing cyclic frequency shift loop, this method can achieve a doubling of the number of multi-carriers under the same number of cyclic frequency shift cycles. For example, for the existing cyclic frequency shifted fiber light source, a new carrier frequency is generated with each cycle, so the number of carriers output after N cycles is N+1. However, for this method, when the number of cycles N≤n-1, the number of new carrier frequencies generated with each cycle is 4N+1, so the number of carriers output after N cycles is (N+1)×(2N+1); when N>n-1, the number of new carrier frequencies generated with each cycle is 2n+1, so the number of carriers output after N cycles is N×(2n+1)+1.

[0064] The method of this application has low multi-carrier noise when outputting the same number of carriers. This is because by adding an adjustable time delay line (TDL), the multi-carrier optical signal generated in each iteration and its frequency-shifted multi-carrier signal are simultaneously coupled to the electro-optical modulator (EOM) for double-sideband modulation. Compared with existing cyclic frequency-shifted light sources, the number of cycles required when outputting the same number of carriers is reduced exponentially, thereby effectively reducing the noise accumulation of light in the cyclic structure and improving the signal-to-noise ratio of the multi-carrier.

[0065] In order to enable those skilled in the art to further understand the method of the present application, the following Figure 2 , the frequencies of RF signal source 1 (RF1) and RF signal source 2 (RF2) are f m and 2f m (n=2) is taken as an example to explain in detail the novel method for multiplying the number of carriers of a cyclic frequency shifted multi-carrier fiber light source. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of them.

[0066] like Figure 2 As shown in the figure, the specific steps of the entire cyclic transmission process are as follows:

[0067] S1. The feedback laser DFB-LD generates an initial seed light with a narrow linewidth continuous wave and a frequency of f0 and inputs it into the beam splitting coupler 1 (OC1).

[0068] S2, the first beam splitter coupler (OC1) splits the initial seed light into two beams. One output end of the first beam splitter coupler (OC1) is connected to the optical delay line, so that the second seed light after the splitting is delayed for a certain time and then obtained at the position ① of one input end of the beam combining coupler (OC3). The other output port of the first beam splitter coupler (OC1) is connected to the input end of the single sideband modulator (SSB), using the frequency f m The RF signal drives the single sideband modulator (SSB), which generates single sideband modulation for the first seed beam input, and generates a frequency interval of f for the first seed beam input. m The frequency shift is achieved by frequency-shifting the beam, and the new frequency carrier is obtained at the other input terminal of the beam-combining coupler (OC3) at position ②. By adjusting the time delay line (TDL), the seed light at position ① and the seed light at position ② can be synchronized in time.

[0069] S3. The seed light and its frequency shifted frequency are obtained at the output end ③ of the beam combining coupler (OC3) and input into the electro-optic modulator (EOM) together.

[0070] S4, the electro-optical modulator (EOM) performs double-sideband modulation on each input optical carrier frequency, and the modulation frequency is 2fm , the double-sideband modulated carrier component is obtained at the output end ④ of the electro-optical modulator (EOM).

[0071] S5, S1-S4 are the processes when the number of cycles N=1. The results are output through one output terminal of the second beam splitter coupler (OC2). At this time, the number of multi-carriers output is 6. Figure 3 As shown. Figure 3 In the figure, the spectra at positions ①②③④ are listed in detail, where f0 is the seed light frequency, f m is the frequency interval of RF source 1.

[0072] S6. The other output port of the second splitter coupler (OC2) is connected to an input port of the first splitter coupler (OC1). The multi-carrier obtained when N=1 is input into the first splitter coupler (OC1) as a new seed light.

[0073] Repeat steps S1-S4, which is a process with a cycle number N=2. Figure 4 As shown, the example Figure 2 The output spectrum at positions ①②③④ is shown in the figure, where f0 is the seed light frequency, f m is the frequency interval of RF source 1, and the number of multi-carriers output at this time is 11.

[0074] The part of the multi-carrier signal that is the feedback signal is again used as the seed light to be input into the beam splitter coupler 1 (OC1), and steps S1-S4 are repeated to complete the next cycle. After N cycles, 5N+1 multi-carrier outputs are finally obtained.

[0075] From the above analysis, it can be seen that the present invention couples the seed light into the electro-optical modulator after passing it through a time delay line and a single-sideband modulator respectively, and realizes the rapid multiplication of the number of multi-carriers through the cyclic structure, thereby solving the problems of the traditional cyclic frequency-shifted multi-carrier fiber light source with a small number of carriers and rapid noise accumulation.

[0076] This application also proposes a system for multiplying the number of carriers of a cyclic frequency-shifted multi-carrier optical fiber light source, the structure of which is as follows: Figure 2As shown, it includes: a distributed feedback laser (DFB-LD) for generating narrow-linewidth continuous-wave seed light, a beam splitter coupler (OC1) for splitting the seed light into two beams, a single-sideband modulator (SSB) connected to an output end of the beam splitter coupler (OC1) and performing frequency shift processing on the first beam of seed light, a time delay line (TDL) connected to the other output end of the beam splitter coupler (OC1) and used for delaying the second beam of seed light, a beam combining coupler (OC3) for synchronously coupling the delayed light with the frequency-shifted light, an electro-optical modulator (EOM) for performing double-sideband modulation on the synchronously coupled light, and a beam splitter coupler (OC2) for dividing the modulated optical signal into an output end and a feedback end, and the feedback end is connected to the input end of the beam splitter coupler (OC1) to form a cyclic structure.

[0077] In this embodiment, an input end of the first beam splitter coupler (OC1) is connected to an output end of the second beam splitter coupler (OC2), and the output end of the first beam splitter coupler (OC1) is connected to the input end of the single sideband modulator (SSB); the output end of the single sideband modulator (SSB) is connected to an input end of the beam combining coupler (OC3), the output end of the beam combining coupler (OC3) is connected to the input end of the electro-optical modulator (EOM), and the output end of the electro-optical modulator (EOM) is connected to the input end of the second beam splitter coupler (OC2).

[0078] Furthermore, the single sideband modulator (SSB) is composed of a frequency of f m The electro-optical modulator (EOM) is driven by a radio frequency signal source 1 (RF1) with a frequency of nf m It is driven by radio frequency signal source 2 (RF2), where n is a positive integer greater than 1.

[0079] A single cycle of the cyclic structure includes: the light is frequency-shifted by the single sideband modulator (SSB) to generate a frequency interval of f m The carrier wave is synchronously input into the electro-optical modulator (EOM) for double-sideband modulation with the delayed seed light to generate a frequency interval of nf m New carrier.

[0080] A portion of each carrier frequency is output as the output of the light source through one output port of the second beam splitter coupler (OC2) connected to the output end of the electro-optical modulator (EOM). The remaining portion is output through the other output port of the second beam splitter coupler (OC2) and input as a new seed light to the other input port of the first beam splitter coupler (OC1). The aforementioned process is repeated for high-speed iteration to output a multi-carrier optical signal, completing the cyclic multiplication process of the number of carriers.

[0081] The present application designs a method and system for multiplying the number of carriers in a cyclic frequency-shifted multi-carrier fiber light source. Under the same number of cycles, the number of carriers is significantly higher than that of traditional methods. By reducing the number of cycles, noise accumulation can be effectively reduced and the signal-to-noise ratio of the multi-carrier signal can be improved. Moreover, the output multi-carrier signal covers a wider spectral range and is suitable for a variety of application scenarios. By adjusting the RF signal frequency and the number of cycles, the number of carriers and the frequency interval can be flexibly controlled.

[0082] The above embodiments of the present application are described in detail. The contents described are only preferred embodiments of the present application and should not be considered to limit the scope of implementation of the present application. All equivalent changes and improvements made within the scope of the present application should still fall within the scope of the patent application.

Claims

1. A method for multiplying the number of carriers of a cyclic frequency shifted multi-carrier optical fiber light source, characterized in that the steps include: A laser light source is used to generate an initial seed light signal; The initial seed light signal is split into two beams by a beam splitting coupler 1, and the first beam of seed light signal is subjected to frequency shift processing; Delaying the second seed optical signal to synchronize it with the frequency-shifted optical signal; The synchronized optical signals are coupled and then subjected to double-sideband modulation; The modulated optical signal is split into an output signal and a feedback signal through a beam splitting coupler, and the feedback signal is re-input into the beam splitting coupler for cyclic processing to achieve iterative multiplication of the number of carriers.

2. The method according to claim 1, characterized in that The laser light source is a distributed feedback laser, and the initial seed light signal generated by the laser light source is a continuous wave light signal with a narrow linewidth and a frequency of f0.

3. The method according to claim 1 or 2, characterized in that The first seed light signal is processed by a single-sideband modulator to generate a signal with a frequency shift of f m Frequency-shifted optical signal; The second seed optical signal is processed through a time delay line; the delay amount of the time delay line can be dynamically adjusted according to the transmission time of the optical signal in the system.

4. The method according to claim 3, characterized in that The step of coupling the synchronized optical signals and then performing double-sideband modulation includes: A beam-combining coupler is used to synchronously couple the delayed light and the frequency-shifted light; Then the coupled light is double-side-band modulated by an electro-optical modulator with a modulation frequency of nf m , where n is a positive integer greater than 1.

5. The method according to claim 4, characterized in that The first beam splitter coupler is a 2×2 optical coupler.

6. The method according to claim 4 or 5, characterized in that The single sideband modulator is composed of a frequency f m The electro-optical modulator is driven by a radio frequency signal source 1 with a frequency of nf m It is driven by a radio frequency signal source 2, and n is a positive integer greater than 1.

7. The method according to claim 6, characterized in that The RF signal source 1 and the RF signal source 2 are both medium- and low-frequency RF signal sources.

8. The method according to any one of claims 1-2, 4-5, and 7, characterized in that: The relationship between the number of cycles N and the number of newly generated carrier frequencies is: When the number of cycles N≤n-1, the number of new carrier frequencies generated in each cycle is 4N+1, and the number of carrier frequencies output after N cycles is (N+1)×(2N+1); When the number of cycles N>n-1, the number of new carrier frequencies generated in each cycle is 2n+1, and the number of carrier frequencies output after N cycles is N×(2n+1)+1.

9. A system for multiplying the number of carriers of a cyclic frequency shifted multi-carrier optical fiber light source, characterized in that: include: Distributed feedback lasers for generating narrow-linewidth continuous-wave seed light; Beam splitting coupler 1, splits the seed light into two beams; a single-sideband modulator connected to an output end of the first beam splitter coupler and performing frequency shift processing on the first seed light beam; a time delay line connected to the other output end of the first beam splitter coupler and used for delaying the second beam of seed light; A beam-combining coupler is used to synchronously couple the delayed light with the frequency-shifted light; Electro-optical modulator, which performs double-sideband modulation on the synchronously coupled light; The second beam splitter coupler divides the modulated optical signal into an output end and a feedback end, and the feedback end is connected to the input end of the first beam splitter coupler to form a loop structure.

10. The system according to claim 9, characterized in that The single sideband modulator is composed of a frequency f m The electro-optical modulator is driven by a radio frequency signal source 1 with a frequency of nf m The RF signal source 2 is driven, and n is a positive integer greater than 1; The single cycle process of the cycle structure includes: after the light is frequency-shifted by the single sideband modulator, the frequency interval is f m The carrier wave is synchronously input into the electro-optical modulator for double-sideband modulation with the delayed seed light to generate a frequency interval of nf m New carrier.

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