Method and system for realizing cyclic shift frequency multiplication of multi-carrier fiber light source

Abstract

The application discloses a method and system for realizing cyclic frequency shift multiplication of a carrier number of a multicarrier fiber light source, and steps include: generating an initial seed light signal by using a laser light source; dividing the initial seed light signal into two beams by a beam splitting coupler one, performing frequency shift processing on the first seed light signal; performing delay processing on the second seed light signal to synchronize the second seed light signal with the light signal after frequency shift; coupling the synchronized light signals and then performing double sideband modulation; dividing the modulated light signal into an output signal and a feedback signal by a beam splitting coupler two, and inputting the feedback signal into the beam splitting coupler one again to perform cyclic processing, thereby realizing iterative multiplication of the carrier number. According to the application, the carrier number is significantly higher than that of a traditional method under the same cycle number; the cycle number can be reduced to effectively reduce noise accumulation and improve the signal-to-noise ratio of the multicarrier signal; and the output multicarrier signal has a wide coverage spectrum range, is suitable for various application scenarios, and can flexibly control the carrier number and frequency interval.

Description

Technical Field

[0001] This application belongs to the field of optical fiber communication and spectroscopy technology, specifically relating to a method and system for doubling the number of carriers in a cyclic frequency-shifted multi-carrier optical fiber light source, applicable to scenarios requiring high-density multi-carrier light sources such as optical communication, optical fiber sensing, and microwave photonics. Background Technology

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

[0003] Carrier quantity limitation: Although theoretically the number of carriers can be increased by increasing the number of loops, in practice, noise accumulation will deteriorate rapidly with the increase of the number of loops, which limits the increase in the number of carriers.

[0004] Low signal-to-noise ratio: Repeated cycles cause a significant decrease in the signal-to-noise ratio of the optical signal, affecting system performance.

[0005] Inefficient: Traditional methods can only generate a limited number of carriers with the same number of cycles, making it difficult to meet the demand for high-density carriers. Summary of the Invention

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

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

[0008] A method for doubling the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source includes the following steps:

[0009] The initial seed light signal is generated using a laser light source;

[0010] The initial seed light signal is split into two beams by a beam splitter coupler. The first beam of seed light signal is frequency-shifted, and the second beam of seed light signal is delayed to synchronize it with the frequency-shifted light signal.

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

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

[0013] Furthermore, the laser source is a distributed feedback laser, and the initial seed light signal it generates 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 f. m Frequency-shifted optical signal;

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

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

[0017] A beam combiner is used to synchronously couple the delayed light to the frequency-shifted light.

[0018] The coupled light is then subjected to double-sideband modulation via an electro-optic modulator at a modulation frequency of nf. m , where n is a positive integer greater than 1.

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

[0020] Furthermore, the single-sideband modulator has a frequency of f m The radio frequency signal source 1 drives the electro-optic modulator; the electro-optic modulator is driven by a frequency of nf m Driven by radio frequency signal source 2, where n is a positive integer greater than 1;

[0021] Furthermore, both the radio frequency signal source 1 and the radio frequency signal source 2 are mid-to-low frequency radio frequency signal sources.

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

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

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

[0025] A system for multiplying the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source includes:

[0026] Distributed feedback lasers are used to generate narrow-linewidth continuous-wave seed light.

[0027] Beam splitter 1 splits the seed light into two beams;

[0028] A single-sideband modulator is connected to one output of the beam splitter coupler to perform frequency shifting on the first seed beam.

[0029] A time delay line is connected to another output terminal of the first beam splitter coupler to delay the second seed light.

[0030] A beam combiner is used to synchronously couple delayed light with frequency-shifted light.

[0031] Electro-optic modulator for double-sideband modulation of synchronously coupled light;

[0032] Beam splitter 2 splits the modulated optical signal into an output end and a feedback end. The feedback end is connected to the input end of beam splitter 1 to form a loop structure.

[0033] Furthermore, the single-sideband modulator has a frequency of f m The radio frequency signal source 1 drives the electro-optic modulator; the electro-optic modulator is driven by a frequency of nf m Driven by radio frequency signal source 2, where n is a positive integer greater than 1;

[0034] A single cycle 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, synchronized with the delayed seed light, is input to the electro-optic modulator for double-sideband modulation, generating a frequency interval of nf. m The new carrier wave.

[0035] The present application discloses a method and system for doubling the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source. Under the same number of cycles, the number of carriers is significantly higher than that of traditional methods. Furthermore, 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 various application scenarios. By adjusting the radio frequency signal frequency and the number of cycles, the number of carriers and the frequency interval can be flexibly controlled. Attached Figure Description

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

[0037] Figure 2 This is a schematic diagram of the transmission system in this application that doubles the number of carriers of a multi-carrier fiber optic light source.

[0038] Figure 3 This is a schematic diagram of the spectral changes when the number of cycles N=1 in this application;

[0039] Figure 4 This is a schematic diagram of the spectral changes when the number of cycles N=2 in this application. Detailed Implementation

[0040] Existing designs involve injecting seed light and passing it through a single-sideband modulator in a cyclic frequency-shifting loop to generate a certain frequency shift. A portion of this shift is output at the cyclic frequency-shifting loop's output, while the remainder circulates through the loop again, ultimately resulting in a multi-carrier output with the frequency shift as the frequency interval. The frequency interval of the multi-carriers is always equal to the frequency of the RF signal driving the modulator; the number of multi-carriers generated depends on the number of loops within the loop. Although theoretically, the cyclic frequency-shifting-based multi-carrier fiber optic light source generation method overcomes the limitation of modulator bandwidth on the number of carriers, allowing for an increase in the number of loops, in practice, noise accumulation in the loop increases rapidly with the number of loops, leading to a significant deterioration in the signal-to-noise ratio and limiting the final output number of multi-carriers. Therefore, the focus of this invention is to optimize the optical path design and modulation method to achieve rapid multiplication of the number of carriers and effective noise suppression.

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

[0042] This application provides a method for doubling the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source, and its transmission flowchart is as follows: Figure 1 As shown, the corresponding schematic diagram of the loop structure is as follows: Figure 2 As shown, the steps include:

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

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

[0045] S2. The initial seed light signal is split into two beams by the beam splitter coupler (OC1). The first beam of seed light signal is frequency shifted. The second beam of seed light signal is delayed to synchronize it with the frequency shifted light signal.

[0046] The initial seed light signal is input into the beam splitter coupler (OC1), and the initial seed light signal is split into two beams by the beam splitter coupler (OC1), namely the first seed light signal and the second seed light signal.

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

[0048] The second seed optical signal is delayed using a time delay line (TDL), ensuring that the delayed optical signal is synchronized with the frequency-shifted optical signal before coupling via a beam combiner (OC3). Specifically, the delay time of the TDL is set to synchronize the unshifted and frequency-shifted light at the input of the electro-optic modulator (EOM). The delay amount of the TDL can be dynamically adjusted based on the transmission time of the optical signals in the system to ensure strict synchronization of the two optical signals.

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

[0050] Specifically, this involves first using a beam combiner (OC3) to synchronously couple the delayed light to the frequency-shifted light; then using an electro-optic modulator (EOM) to perform double-sideband modulation on the coupled light at a modulation frequency of nf. m Where n is a positive integer greater than 1. The two optical signals are synchronously coupled and then input into an electro-optic modulator (EOM) for double-sideband modulation, generating a frequency interval of nf. m The new carrier, n is a positive integer greater than 1.

[0051] In this embodiment, beam splitter coupler 1 (OC1) is a 2×2 optical coupler.

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

[0053] S4. The modulated optical signal is split into an output signal and a feedback signal by the second beam splitter (OC2), and the feedback signal is re-input to the first beam splitter for cyclic processing to achieve iterative multiplication of the number of carriers.

[0054] The modulated optical signal is split into two beams by beam splitter coupler 2 (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 (OC1) for cyclic processing. By controlling the number of cycle N, the number of carriers is multiplied, thereby achieving iterative multiplication of the number of carriers. A single cycle includes: the light is frequency-shifted by a single-sideband modulator (SSB) to generate a frequency interval of f. mThe carrier wave, synchronized with the delayed seed light, is input to the electro-optic modulator (EOM) for double-sideband modulation, generating a frequency interval of nf. m The new carrier wave.

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

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

[0058] When the number of cycles N > n-1, the number of newly generated carrier frequencies 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 the initial seed light, and a beam splitter coupler (OC1) is provided for splitting the initial seed light source signal into two seed beams. The two outputs of beam splitter coupler (OC1) are connected to a time delay line (TDL) for delaying the output light and the input of a loop structure for frequency multiplication, respectively. The output of the time delay line (TDL) is connected to the output of a single sideband modulator (SSB) in the loop structure and to the input of a beam combiner coupler (OC3) for combining the two seed beams into one. The output of beam combiner coupler (OC3) is fed into an electro-optic modulator (EOM) in the loop structure to generate frequency multiplication. The frequency-multiplied multicarrier optical signal then enters the input of beam splitter coupler (OC2), which is connected to the output of the electro-optic modulator (EOM). One port of beam splitter coupler 2 (OC2) outputs a portion of the multi-carrier optical signal, while the other output port is connected to another input port of beam splitter coupler 1 (OC1), so that the remaining multi-carrier signal is used as seed light and re-inputted into the loop structure for a new round of frequency multiplication.

[0060] In this embodiment, the loop structure that generates frequency multiplication includes a beam splitter coupler (OC1), a single-sideband modulator (SSB), a beam combiner coupler (OC3), an electro-optic modulator (EOM), and a beam splitter coupler (OC2). One input terminal of beam splitter coupler (OC1) is connected to one output terminal of beam splitter coupler (OC2), and the output terminal of beam splitter coupler (OC1) is connected to the input terminal of the single-sideband modulator (SSB). The output terminal of the single-sideband modulator (SSB) is connected to one input terminal of the beam combiner coupler (OC3), the output terminal of the beam combiner coupler (OC3) is connected to the input terminal of the electro-optic modulator (EOM), and the output terminal of the electro-optic modulator (EOM) is connected to the input terminal of beam splitter coupler (OC2).

[0061] The single-sideband modulator (SSB) has its RF input connected to RF signal source 1 (RF1), and the electro-optic modulator (EOM) has its RF input connected to RF signal source 2 (RF2). Both RF signal source 1 (RF1) and RF signal source 2 (RF2) are mid-to-low frequency RF signal sources, with RF signal source 1 (RF1) having a frequency of f0. m The frequency of radio frequency 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-doubling loop structure through one output port of beam splitter 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 to the time delay line (TDL) through the other output port of beam splitter coupler 1 (OC1), and after time delay, it is frequency shifted by f. m The frequency-shifted light is synchronized in time and fed together into the electro-optic modulator (EOM) via a beam combiner (OC3) for double-sideband modulation. The electro-optic modulator (EOM) modulates the seed light and the frequency-shifted light separately to generate new carrier frequencies. Each carrier frequency is output as a portion of the light source through one output port of beam splitter coupler two (OC2), which is connected to the output of the electro-optic modulator (EOM). The remaining portion is output as a new seed light through the other output port of beam splitter coupler two (OC2) and input to the other input port of beam splitter coupler one (OC1). The process described above is repeated for high-speed iteration, outputting multi-carrier optical signals and completing the cyclic doubling process of the number of carriers.

[0063] The method proposed in this application can double the number of carriers with the same number of cyclic frequency shifting cycles. This is because the proposed cyclic structure synchronously couples the split seed light with the frequency-shifting light, and then modulates it with a double-sideband modulation by a frequency shift of n times. Compared with existing cyclic frequency shifting loops, this method can double the number of carriers with the same number of cyclic frequency shifting cycles. For example, for existing cyclic frequency shifting fiber optic light sources, a new carrier frequency is generated each cycle, so the number of carriers output after N cycles is N+1. For this method, when the number of cycles N≤n-1, the number of newly generated carrier frequencies per 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 newly generated carrier frequencies per cycle is 2n+1, so the number of carriers output after N cycles is N×(2n+1)+1.

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

[0065] To enable those skilled in the art to further understand the method of this application, the following will be described in conjunction with the appendix. Figure 2 The frequencies of radio frequency signal source 1 (RF1) and radio frequency signal source 2 (RF2) are f1 and f2, respectively. m and 2f m Taking (n=2) as an example, the novel method for doubling the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source is described in detail above. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

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

[0067] S1. A narrow-linewidth continuous wave with a frequency of f0 is generated by the feedback laser DFB-LD and input into the beam splitter coupler (OC1).

[0068] S2. Beam splitter coupler 1 (OC1) splits the initial seed light into two beams. One output of beam splitter coupler 1 (OC1) is connected to an optical delay line. The purpose is to delay the second seed light after a certain time and obtain the time-delayed seed light at position ① of one input of beam combiner coupler 3. The other output port of beam splitter coupler 1 (OC1) is connected to the input of a single-sideband modulator (SSB), using a frequency of f m The radio frequency signal drives a single-sideband modulator (SSB), which generates single-sideband modulation on the first input seed light, producing a frequency interval of f. m The frequency shift is achieved, resulting in a new frequency carrier at position ②, the other input terminal of the beam combiner (OC3). By adjusting the time delay line (TDL), the seed light at position ① and position ② can be synchronized in time.

[0069] S3. At position ③ of the output end of the beam combiner (OC3), the seed light and its frequency after frequency shift can be obtained and input together into the electro-optic modulator (EOM).

[0070] S4. The electro-optic modulator (EOM) performs double-sideband modulation on each input optical carrier frequency, with a modulation frequency of 2f.m The double-sideband modulated carrier component is obtained at position ④ of the output terminal of the electro-optic modulator (EOM).

[0071] S5 and S1-S4 represent the process when the number of cycles N = 1. The result is output through one output terminal of beam splitter coupler 2 (OC2), at which point the number of multi-carriers output is 6. Figure 3 As shown. In Figure 3 The image shows the spectrum at positions ①②③④ in detail, where f0 is the seed light frequency, f m The frequency interval of radio frequency source 1.

[0072] S6. The other output port of beam splitter coupler 2 (OC2) is connected to one input port of beam splitter coupler 1 (OC1). When N=1, the multi-carrier obtained is used as a new seed light input into beam splitter coupler 1 (OC1).

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

[0074] The feedback signal from the multi-carrier beam is used again as a seed light input to beam splitter 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] As can be seen from the above analysis, the present invention couples the seed light into the electro-optic modulator after passing through a time delay line and a single sideband modulator, respectively. Through the cyclic structure, the number of multiple carriers is rapidly multiplied, solving the problems of low carrier number and rapid noise accumulation in traditional cyclic frequency shift multi-carrier fiber light sources.

[0076] This application also proposes a system for multiplying the number of carriers in a cyclic frequency-shifted multicarrier fiber optic 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) that splits the seed light into two beams; a single-sideband modulator (SSB) connected to one output of the beam splitter coupler (OC1) and performing frequency shifting on the first seed light; a time delay line (TDL) connected to the other output of the beam splitter coupler (OC1) and performing delaying on the second seed light; a beam combiner coupler (OC3) for synchronously coupling the delayed light with the frequency-shifted light; an electro-optic modulator (EOM) that performs double-sideband modulation on the synchronously coupled light; and a beam splitter coupler (OC2) that splits the modulated optical signal into an output and a feedback end, with the feedback end connected to the input of the beam splitter coupler (OC1) to form a loop structure.

[0077] In this embodiment, one input terminal of beam splitter coupler 1 (OC1) is connected to one output terminal of beam splitter coupler 2 (OC2), and the output terminal of beam splitter coupler 1 (OC1) is connected to the input terminal of single sideband modulator (SSB); the output terminal of single sideband modulator (SSB) is connected to one input terminal of beam combiner coupler (OC3), the output terminal of beam combiner coupler (OC3) is connected to the input terminal of electro-optic modulator (EOM), and the output terminal of electro-optic modulator (EOM) is connected to the input terminal of beam splitter coupler 2 (OC2).

[0078] Furthermore, the single-sideband modulator (SSB) consists of a frequency f m The radio frequency signal source 1 (RF1) drives the electro-optic modulator (EOM) with a frequency of nf m 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: light being frequency-shifted by the single-sideband modulator (SSB) to generate a frequency interval of f. m The carrier wave, synchronized with the delayed seed light, is input to the electro-optic modulator (EOM) for double-sideband modulation, generating a frequency interval of nf. m The new carrier wave.

[0080] Each carrier frequency is output as a portion of the light source through one output port of beam splitter coupler 2 (OC2) connected to the output terminal of the electro-optic modulator (EOM). The remaining portion is output as a new seed light through the other output port of beam splitter coupler 2 (OC2) and input to the other input port of beam splitter coupler 1 (OC1). The process described above is repeated to perform high-speed iteration and output multi-carrier optical signals, completing the cyclic doubling process of the number of carriers.

[0081] The present application discloses a method and system for doubling the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source. Under the same number of cycles, the number of carriers is significantly higher than that of traditional methods. Furthermore, 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 various application scenarios. By adjusting the radio frequency signal frequency and the number of cycles, the number of carriers and the frequency interval can be flexibly controlled.

[0082] The embodiments of this application have been described in detail above. These descriptions are merely preferred embodiments and should not be construed as limiting the scope of this application. All equivalent variations and modifications made within the scope of this application should still fall within the patent coverage of this application.

Claims

1. A method for doubling the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source, characterized by the following steps: include: The initial seed light signal is generated using a laser light source; The initial seed light signal is split into two beams by a beam splitter coupler, and the first beam of seed light signal is frequency shifted. The second seed light signal is delayed to synchronize it with the frequency-shifted light signal; The synchronized optical signal is coupled and then subjected to double-sideband modulation, the modulation frequency of which is n. , where n is a positive integer greater than 1; The modulated optical signal is split into an output signal and a feedback signal by a beam splitter. The feedback signal is then re-inputted into the beam splitter for cyclic processing, achieving iterative doubling of the number of carriers. The relationship between the number of cycles N and the number of newly generated carrier frequencies is as follows: When the number of cycles N≤n-1, the number of newly generated carrier frequencies in each cycle is 4N+1, and the number of output carriers after N cycles is (N+1)×(2N+1). When the number of cycles N > n-1, the number of newly generated carrier frequencies in each cycle is 2n+1, and the number of output carriers after N cycles is N×(2n+1)+1.

2. The method according to claim 1, characterized in that, The laser source is a distributed feedback laser, which generates an initial seed light signal with a narrow linewidth and a frequency of [missing information]. Continuous wave optical signal.

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 frequency shift. Frequency-shifted optical signal; The second seed light signal is processed by a time delay line; the delay amount of the time delay line can be dynamically adjusted according to the transmission time of the light signal in the system.

4. The method according to claim 3, characterized in that, The process of coupling the synchronized optical signal and then performing double-sideband modulation includes: A beam combiner is used to synchronously couple the delayed light to the frequency-shifted light. The coupled light is then subjected to double-sideband modulation via an electro-optic modulator.

5. The method according to claim 4, characterized in that, The 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 has a frequency of The radio frequency signal source 1 drives the electro-optic modulator; the electro-optic modulator is driven by a frequency of n The signal source 2 drives the signal, where n is a positive integer greater than 1.

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

8. A system for multiplying the number of carriers in a cyclic frequency-shifted multi-carrier fiber optic light source, characterized in that, include: Distributed feedback lasers are used to generate narrow-linewidth continuous-wave seed light. Beam splitter 1 splits the seed light into two beams; A single-sideband modulator is connected to one output of the beam splitter coupler to perform frequency shifting on the first seed beam. A time delay line is connected to another output terminal of the first beam splitter coupler to delay the second seed light. A beam combiner is used to synchronously couple delayed light with frequency-shifted light. An electro-optic modulator performs double-sideband modulation on the synchronously coupled light, wherein the modulation frequency of the double-sideband modulation is n. , where n is a positive integer greater than 1; Beam splitter two divides the modulated optical signal into an output terminal and a feedback terminal. The feedback terminal is connected to the input terminal of beam splitter one to form a loop structure. The relationship between the number of loops N and the number of newly generated carrier frequencies is as follows: When the number of cycles N≤n-1, the number of newly generated carrier frequencies in each cycle is 4N+1, and the number of output carriers after N cycles is (N+1)×(2N+1). When the number of cycles N > n-1, the number of newly generated carrier frequencies in each cycle is 2n+1, and the number of output carriers after N cycles is N×(2n+1)+1.

9. The system according to claim 8, characterized in that, The single-sideband modulator has a frequency of The radio frequency signal source 1 drives the electro-optic modulator; the electro-optic modulator is driven by a frequency of n Driven by radio frequency signal source 2, where n is a positive integer greater than 1; A single cycle of the cyclic structure includes: after the light is frequency-shifted by the single-sideband modulator, a frequency interval is generated. The carrier wave, synchronized with the delayed seed light, is input to the electro-optic modulator for double-sideband modulation, generating a frequency interval of n. The new carrier wave.

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