Single-resonant-cavity double-optical-frequency-comb light source based on double phase shifters

Abstract

The invention discloses a single-resonant-cavity double-optical-frequency-comb light source based on double phase shifters, and the light source comprises a polarization-maintaining optical fiber coupler, a polarization-maintaining gain optical fiber, the double phase shifters and an output device which are sequentially connected through polarization-maintaining optical fibers, the output module is used for outputting optical signals input by different input ends through corresponding output ends according to requirements; the polarization-maintaining gain optical fiber is used for amplifying an optical signal excited by the pumping laser output by the polarization-maintaining optical fiber coupler; the double phase shifters are used for constructing nonlinear amplification loop reflectors on the fast axis and the slow axis of the polarization maintaining optical fiber at the same time and generating cross-polarization double optical frequency combs in a single resonant cavity in a polarization multiplexing mode; and the output device is used for outputting the dual-optical frequency comb. Therefore, the double-phase shifter can be used for realizing large-range flexible adjustment of the repetition frequency difference of the double-optical frequency comb.

Description

Technical Field

[0001] The invention relates to a single-resonance cavity dual-optical frequency comb light source based on a dual phase shifter, and relates to the technical field of optics. Background Art

[0002] The emergence of optical frequency combs has brought revolutionary development to the field of optical precision metrology. Due to its advantages of multi-band coverage, wide spectral width, independent resolution of longitudinal modes and ultra-high frequency stability, it has been applied to time reference and time-frequency transfer, distance measurement, spectroscopy and other fields. Dual optical frequency comb technology has the advantages of wide spectrum, high resolution and fast rate. In order to obtain phase-stable and longitudinal mode-resolved interference signals, it is necessary to ensure good mutual coherence between the two optical frequency combs.

[0003] The dual optical frequency comb technology uses two optical frequency combs with a small repetition frequency difference for measurement. One optical frequency comb is used as a signal light to detect the distance or spectrum to be measured, and the other optical frequency comb is used as a local oscillator light to perform asynchronous optical sampling of the signal light. The optical frequency domain containing the information to be measured is mapped to the radio frequency domain by multi-heterodyne interference, and the phase information in the optical frequency domain can be solved by low-frequency detection. Therefore, the dual optical frequency comb technology also provides a powerful tool for dynamic and high-precision measurement, and is the development direction of high-precision measurement in the future. In order to obtain phase-stable and longitudinal-mode-resolved interference signals, it is necessary to ensure that the two optical frequency combs have narrow optical longitudinal mode linewidths, or have sufficiently good mutual coherence between the two, which is the core of the dual optical frequency comb technology. In the early stage, the dual optical frequency comb technology used a continuous laser locked to an ultra-stable cavity to beat with the optical frequency comb, and used a high-feedback-bandwidth actuator to tightly lock the beat signal to obtain an optical frequency comb light source with extremely high optical frequency stability; another method is the post-processing correction method, which directly compensates for the noise of the interference signal after obtaining the relative fluctuation between the dual optical frequency combs, and can use analog signal processing or digital signal correction. Both of the above technologies require relatively complex feedback systems or signal processing modules to achieve noise suppression, and are relatively expensive, which limits the further application of dual optical frequency comb technology in the field of precision metrology.

[0004] Different from the above two active locking technologies, the single-cavity dual-comb technology generates dual optical frequency combs based on a single optical resonant cavity. Since the two optical frequency combs share a resonant cavity, the common-mode noise between the two can be passively suppressed, and they naturally have good mutual coherence. The single-cavity dual-comb technology usually reuses a certain characteristic of the resonant cavity to obtain dual optical frequency combs, such as different propagation directions of the ring resonator, different operating wavelengths, and different pulse polarizations. However, the method of generating dual optical frequency combs based on the single-cavity dual-comb technology usually faces the problem of small repetition frequency difference and small tuning range, which is not convenient to use. Therefore, designing a new single-cavity dual-comb light source with long-term stability and flexible repetition frequency difference tuning is still the direction of research efforts. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, in view of the above problems, the purpose of the present invention is to provide a single-resonant cavity dual-optical frequency comb light source based on a dual phase shifter that can generate a certain repetition frequency difference and the repetition frequency difference can be flexibly adjusted over a wide range.

[0006] In order to achieve the purpose of the invention, the technical solution adopted by the present invention is:

[0007] The present invention provides a single-resonant cavity dual-optical frequency comb light source based on a dual phase shifter, the light source comprising:

[0008] A pump source, used to generate pump laser;

[0009] The laser resonant cavity comprises a polarization-maintaining fiber coupler, a polarization-maintaining gain fiber, a dual phase shifter and an output device which are sequentially connected through a polarization-maintaining fiber, wherein:

[0010] The polarization-maintaining fiber coupler is used to output optical signals input from different input ends through corresponding output ends as required;

[0011] The polarization-maintaining gain optical fiber is used to amplify the optical signal excited by the pump laser output by the polarization-maintaining optical fiber coupler;

[0012] The dual phase shifter is used to construct a nonlinear amplifying loop reflector simultaneously on the fast and slow axes of the polarization-maintaining optical fiber to generate dual optical frequency combs of orthogonal polarizations in a single resonant cavity in a polarization multiplexing manner;

[0013] The output device is used to output a dual optical frequency comb.

[0014] In a preferred embodiment, it also includes a polarization-maintaining fiber wavelength division multiplexer for inputting the pump laser into the polarization-maintaining fiber coupler, and the polarization-maintaining fiber wavelength division multiplexer is provided with a first reflection end and a second reflection end, the first reflection end is connected to the pump laser, and the second reflection end is connected to the polarization-maintaining fiber coupler.

[0015] In a preferred embodiment, the polarization-maintaining fiber coupler is provided with a first port, a second port, a third port and a fourth port, and the dual phase shifter is provided with a port one and a port two; the first port is connected to the second reflection end, the second port is connected to the port one through the polarization-maintaining gain fiber, the port two is connected to the third port, and the fourth port is connected to the output device.

[0016] In a preferred embodiment, the dual phase shifter includes a first polarization-maintaining fiber collimator, a second polarization-maintaining fiber collimator, a polarization beam splitter, a first Faraday rotator, a second Faraday rotator, a first wave plate, a second wave plate, a first reflector, and a second reflector; light transmitted on the slow axis of the first polarization-maintaining fiber collimator is transmitted through the polarization beam splitter prism and then reflected by the first Faraday rotator, the first wave plate, and the first reflector in sequence, the reflected light returns along the original optical path and passes through the first wave plate and the first Faraday rotator again, is reflected by the polarization beam splitter prism, and is received by the slow axis of the second polarization-maintaining fiber collimator; light transmitted on the fast axis of the first polarization-maintaining fiber collimator is reflected through the polarization beam splitter prism and then is reflected by the second Faraday rotator, the second wave plate, and the second reflector in sequence, the reflected light passes through the second wave plate and the second Faraday rotator in sequence, and is transmitted by the polarization beam splitter prism, and the light transmitted through the beam splitter prism is received by the fast axis of the second polarization-maintaining fiber collimator;

[0017] Among them, the dual phase shifter is used to simultaneously construct nonlinear amplification loop reflectors on the fast and slow axes of the polarization-maintaining optical fiber. The positions of the first reflector and the second reflector respectively determine the repetition frequencies of the two optical frequency combs. Moving the corresponding reflectors along the propagation direction of the light can independently adjust the repetition frequencies of the respective optical frequency combs.

[0018] In a preferred embodiment, the slow axis or fast axis of the first polarization-maintaining fiber collimator is rotated 90 degrees relative to the slow axis or fast axis of the second polarization-maintaining fiber collimator to ensure that light is always transmitted along the slow axis or fast axis.

[0019] In a preferred embodiment, the first Faraday rotator and the second Faraday rotator rotate the incident linear polarization light by 45 degrees in the same direction.

[0020] In a preferred embodiment, the fast axes of the first wave plate and the second wave plate are 45° to the horizontal plane, and the fast axes of the first wave plate and the second wave plate are perpendicular to each other in space; or;

[0021] The slow axes of the first wave plate and the second wave plate form an angle of 45° with the horizontal plane, and the slow axis of the first wave plate and the slow axis of the second wave plate are perpendicular to each other in space.

[0022] In a preferred embodiment, the polarization-maintaining gain optical fiber is a polarization-maintaining erbium-doped optical fiber or a polarization-maintaining ytterbium-doped optical fiber.

[0023] In a preferred embodiment, the output device uses a polarization-maintaining fiber half-reflecting and half-mirror, and the polarization-maintaining fiber half-reflecting and half-mirror serves as an end mirror of the laser resonant cavity and outputs a dual optical frequency comb.

[0024] In a preferred embodiment, the output device further comprises a grating device for performing dispersion compensation on the laser resonant cavity.

[0025] Due to the adoption of the above technical scheme, the present invention has the following characteristics: the single-resonance cavity dual optical frequency comb light source based on the dual phase shifter provided by the present invention, the polarization-maintaining fiber coupler, the polarization-maintaining gain fiber, the dual phase shifter and the output device are used to form a laser resonant cavity, generate and output an optical frequency comb, and the nonlinear amplification loop reflector is simultaneously constructed on the fast and slow axes of the polarization-maintaining fibers of each device in the laser resonant cavity through the dual phase shifter, and the orthogonal polarization dual optical frequency comb output is realized in a single polarization-maintaining laser resonant cavity in a polarization multiplexing manner, and it has a longer-term stability compared to the mode-locking method using a solid saturable absorber. The dual phase shifter of the present invention can realize a wide range of flexible adjustment of the repetition frequency difference of the dual optical frequency comb, and the adjustment range of the repetition frequency difference is not limited by the mode-locking mechanism, but depends on the collimation and coupling degree of the polarization-maintaining fiber collimator. In summary, the present invention can be widely used in the production of dual optical frequency combs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings:

[0027] Figure 1 Schematic diagram of a single-resonance dual-optical frequency comb structure based on a dual phase shifter according to an embodiment of the present invention.

[0028] Figure 2 Graph 1 is an output performance curve of an embodiment of the present invention. DETAILED DESCRIPTION

[0029] It should be understood that the terms used in the text are only for the purpose of describing specific example embodiments, and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" as used in the text may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0030] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0031] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0032] Since the method of generating dual optical frequency combs by single-cavity dual-comb technology usually faces the problems of small repetition frequency difference and small tuning range, it is not convenient to use. The single-resonant cavity dual optical frequency comb light source based on dual phase shifter provided by the present invention includes: a pump source for generating pump laser; a laser resonant cavity, including a polarization-maintaining fiber coupler, a polarization-maintaining gain fiber, a dual phase shifter and an output device connected in sequence by polarization-maintaining fiber, wherein: a polarization-maintaining fiber coupler, for outputting optical signals input from different input ends through corresponding output ends as required; a polarization-maintaining gain fiber, for amplifying optical signals excited by the pump laser output by the polarization-maintaining fiber coupler; a dual phase shifter, for simultaneously constructing a nonlinear amplification loop reflector on the fast and slow axes of the polarization-maintaining fiber, to generate orthogonally polarized dual optical frequency combs in a single resonant cavity in a polarization multiplexing manner; an output device, for outputting a dual optical frequency comb. Therefore, the dual phase shifter of the present invention can be used to realize flexible adjustment of the repetition frequency difference of the dual optical frequency comb over a wide range.

[0033] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0034] like Figure 1As shown, the single-cavity dual-optical frequency comb light source based on a dual phase shifter provided in this embodiment is implemented based on a fiber mode-locked laser, and includes a pump source 1, a polarization-maintaining fiber wavelength division multiplexer 2 and a laser cavity, wherein the laser cavity includes a polarization-maintaining fiber coupler 3, a polarization-maintaining gain fiber 4, a dual phase shifter 5 and an output device 6 connected in sequence through a polarization-maintaining fiber.

[0035] A pump source 1 is used to generate a pump laser. The pump laser is emitted to a polarization-maintaining fiber wavelength division multiplexer 2 through a standard polarization-maintaining fiber. The polarization-maintaining fiber wavelength division multiplexer 2 uses optical wavelength multiplexing technology to allow light of different wavelengths to be transmitted simultaneously in the device, and is used to input the pump laser generated by the pump source 1 into the laser resonant cavity. The laser emitted from the polarization-maintaining fiber wavelength division multiplexer 2 is emitted to a dual phase shifter 5 through a polarization-maintaining fiber coupler 3 and a polarization-maintaining gain fiber 4. The polarization-maintaining fiber coupler 3 has more than one input or output end, and the optical signal input from the input end can be output through the corresponding output end in different proportions. The polarization-maintaining gain fiber 4 is a polarization-maintaining single-mode fiber doped with gain rare earth ions. The doped rare earth ions can be used to amplify the optical signal after being excited by the pump laser. The dual phase shifter 5 is used to simultaneously construct a nonlinear amplification loop reflector on the fast and slow axes of the polarization-maintaining fibers of each device in the laser resonant cavity, and to generate orthogonally polarized dual optical frequency combs in a single resonant cavity in a polarization multiplexing manner. The output device 6 is connected to the dual phase shifter 5 via the polarization-maintaining fiber coupler 3 for outputting the dual optical frequency comb.

[0036] In a preferred embodiment of the present invention, the polarization-maintaining fiber wavelength division multiplexer 2 is provided with a reflection end 2a and a reflection end 2b. The polarization-maintaining fiber coupler 3 is provided with a port 3a, a port 3b, a port 3c and a port 3d. The dual phase shifter 5 is provided with a port 5a and a port 5b. The pump source 1 is connected to the reflection end 2a of the polarization-maintaining fiber wavelength division multiplexer 2, and the pump light is reflected to the reflection end 2b and connected to the port 5a of the dual phase shifter 5 through the ports 3a and 3b of the polarization-maintaining fiber coupler 3 through the polarization-maintaining gain fiber 4, and the port 5b of the dual phase shifter 5 is connected to the port 3c of the polarization-maintaining fiber coupler 3. The port 3d of the polarization-maintaining fiber coupler 3 is connected to the output device 6.

[0037] Furthermore, two ends of the polarization-maintaining gain fiber 4 are fused to the port 3 b of the polarization-maintaining fiber coupler 3 and the port 5 a of the dual phase shifter 5 , respectively, and the port 5 b of the dual phase shifter 5 is fused to the port 3 c of the polarization-maintaining fiber coupler 3 .

[0038] In a preferred embodiment of the present invention, the dual phase shifter 5 includes a first polarization-maintaining fiber collimator 51, a second polarization-maintaining fiber collimator 56, a polarization splitter prism 52, a first Faraday rotator 53, a second Faraday rotator 57, a first eighth wave plate 54, a second eighth wave plate 58, a first reflector 55 and a second reflector 59.

[0039] The light transmitted on the slow axis of the first polarization-maintaining fiber collimator 51 is transmitted through the polarization beam splitter prism 52 and then reflected by the first Faraday rotator 53, the first eighth wave plate 54 and the first reflector 55 in sequence. The reflected light returns along the original optical path and passes through the first eighth wave plate 54 and the first Faraday rotator 53 again. The light is reflected by the polarization beam splitter prism 52 and then received by the slow axis of the second polarization-maintaining fiber collimator 56.

[0040] The light transmitted on the fast axis of the first polarization-maintaining fiber collimator 51 is reflected by the polarization beam splitter prism 52 and then sequentially reflected by the second Faraday rotator 57, the second eighth-wave plate 58 and the second reflector 59. The reflected light sequentially passes through the second eighth-wave plate 58 and the second Faraday rotator 57 and is transmitted by the polarization beam splitter prism 52. The light transmitted by the beam splitter prism 52 is received by the fast axis of the second polarization-maintaining fiber collimator 56.

[0041] Among them, the dual phase shifter 5 is used to simultaneously construct nonlinear amplification loop reflectors on the fast and slow axes of the polarization-maintaining optical fibers of each device in the laser resonant cavity. The dual phase shifter 5 can be used for flexibly tuning the repetition frequency difference of the dual optical frequency combs; the positions of the first reflector 55 and the second reflector 59 in the dual phase shifter 5 respectively determine the repetition frequencies of the two optical frequency combs, and the repetition frequencies of the respective optical frequency combs can be independently adjusted by moving the corresponding reflectors along the propagation direction of the light. Therefore, by changing the relative positions of the first reflector 55 and the second reflector 59 in the dual phase shifter 5, the repetition frequency difference can be tuned from zero to almost any value, and the maximum tuning range depends on the coupling degree of the first polarization-maintaining fiber collimator 51 and the second polarization-maintaining fiber collimator 56 with the first reflector 55 and the second reflector 59.

[0042] Furthermore, the slow axis (fast axis) of the first polarization-maintaining fiber collimator 51 is rotated 90 degrees relative to the slow axis (fast axis) of the second polarization-maintaining fiber collimator 56, so as to ensure that the light is always transmitted along the slow axis (fast axis). The slow axis of the first polarization-maintaining fiber collimator 51 can be perpendicular to the paper surface or parallel to the paper surface, which is not limited here; however, after the slow axis direction of the polarization-maintaining fiber collimator 51 is determined, the slow axis of the polarization-maintaining fiber collimator 52 needs to be rotated 90 degrees relative to the polarization-maintaining fiber collimator 51, that is, if the slow axis of 51 is perpendicular to the paper surface, then the slow axis of 52 is parallel to the paper surface, and if the slow axis of 51 is parallel to the paper surface, then the slow axis of 52 is perpendicular to the paper surface.

[0043] Furthermore, the first Faraday rotator 53 and the second Faraday rotator 57 rotate the incident linear polarization light by 45 degrees in the same direction.

[0044] Further, the first one-eighth wave plate 54 and the second one-eighth wave plate 58 are used to introduce a linear phase delay in the laser resonant cavity so as to change the transmittance curve of the optical signal in the resonant cavity, and are used to generate a mode-locked pulse. There are many cases of the transmittance curve that can achieve mode locking, corresponding to different wave plate delay amounts, which can be other wave plate delay amounts that are easy to pulse mode lock, such as a sixth wave plate, etc., as an example, but not limited to this. In addition, the fast axes of the first one-eighth wave plate 54 and the second one-eighth wave plate 58 are 45° to the horizontal plane, and the fast axes of the first one-eighth wave plate 54 and the second one-eighth wave plate 58 are perpendicular to each other in space; or; the slow axes of the first one-eighth wave plate 54 and the second one-eighth wave plate 58 are 45° to the horizontal plane, and the first one-eighth wave plate 54 and the second one-eighth wave plate 58 are perpendicular to each other in space.

[0045] In a preferred embodiment of the present invention, the pump source 1 can be a semiconductor laser. The polarization-maintaining fiber wavelength division multiplexer 2 connected to the semiconductor laser 1 can be fused in the laser resonant cavity, that is, located at any one of the polarization-maintaining fiber coupler port 3b or 3c or the polarization-maintaining gain fiber 4 or the dual phase shifter port 5a or 5b, and is used for pumping the gain medium of the laser resonant cavity, and there is no restriction on the position.

[0046] In a preferred embodiment of the present invention, the polarization-maintaining gain fiber 4 can be a polarization-maintaining erbium-doped fiber or a polarization-maintaining ytterbium-doped fiber or other rare earth ion-doped polarization-maintaining gain fiber, and different working media can be used to realize the laser resonant cavity.

[0047] In a preferred embodiment of the present invention, the standard polarization-maintaining optical fiber is a single-mode optical fiber with built-in stress rods, which generates strong birefringence to isolate the polarization state of the light transmitted in the optical fiber from the inhomogeneity generated in the optical fiber manufacturing process or the external environmental disturbance.

[0048] In a preferred embodiment of the present invention, the output device 6 can adopt a polarization-maintaining fiber half-reflecting and half-mirror to reflect part of the optical signal back to the above-mentioned nonlinear amplification loop reflector for resonance to generate laser. The semi-transparent and semi-reflective characteristics enable the polarization-maintaining fiber half-reflecting and half-mirror to serve as both the end mirror of the laser resonant cavity and the output of the laser resonant cavity, that is, the polarization-maintaining fiber half-reflecting and half-mirror serves as the end mirror of the optical resonant cavity and outputs a dual optical frequency comb.

[0049] Furthermore, the output device 6 also includes a grating device for dispersion compensation of the laser resonant cavity. The grating device can be a chirped fiber Bragg grating, which has a certain reflectivity for a specific spectral bandwidth by introducing a non-periodic refractive index distribution in a single-mode optical fiber. At the same time, due to the non-periodic refractive index distribution, group delay dispersion can be introduced. The design of the non-periodic refractive index distribution allows it to be used for dispersion compensation of the laser resonant cavity. In addition, the grating device can also use a spatial device grating pair or a polarization-maintaining dispersion compensation fiber to compensate for the dispersion of the laser resonant cavity, which can achieve the same mode locking effect, which is not limited here.

[0050] In summary, the single-resonance cavity dual optical frequency comb light source based on the dual phase shifter of the present invention forms a laser resonant cavity through a polarization-maintaining fiber coupler 3, a polarization-maintaining gain fiber 4, a dual phase shifter 5 and an output device 6; nonlinear amplification loop reflectors are respectively constructed on the fast and slow axes of the polarization-maintaining fibers of each device in the laser resonant cavity through the dual phase shifter 5, thereby simultaneously generating orthogonally polarized dual optical frequency combs in a single laser resonant cavity; the repetition frequency difference can be flexibly tuned by adjusting the relative positions of the reflectors in the dual phase shifter 5; the laser resonant cavity based on the dual phase shifter can be used to realize a dual optical frequency comb light source with a simple structure, good mutual coherence and flexible repetition frequency difference tuning.

[0051] like Figure 2 As shown, the output light is a dual optical frequency comb with orthogonal polarization and a certain repetition frequency difference; after polarization splitting, two optical frequency combs can be obtained respectively; it can be seen that the output spectra basically overlap, and the spectra have a wider width; the output spectrum has no obvious modulation at the full sweep width, indicating that the dual optical frequency comb light source works in a single-pulse mode-locked state and can be used for optical precision metrology applications; the fundamental frequency spectrum is about 60dB and the crosstalk suppression to the other optical frequency comb can reach more than 30dB.

[0052] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description of reference terms "a preferred embodiment", "further", "specifically", "in the present embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A single-resonant cavity dual-optical frequency comb light source based on a dual phase shifter, characterized in that: The light source includes: A pump source, used to generate pump laser; The laser resonant cavity comprises a polarization-maintaining fiber coupler, a polarization-maintaining gain fiber, a dual phase shifter and an output device which are sequentially connected through a polarization-maintaining fiber, wherein: The polarization-maintaining fiber coupler is used to output optical signals input from different input ends through corresponding output ends as required; The polarization-maintaining gain optical fiber is used to amplify the optical signal excited by the pump laser output by the polarization-maintaining optical fiber coupler; The dual phase shifter is used to construct a nonlinear amplifying loop reflector simultaneously on the fast and slow axes of the polarization-maintaining optical fiber to generate dual optical frequency combs of orthogonal polarizations in a single resonant cavity in a polarization multiplexing manner; The output device is used to output a dual optical frequency comb.

2. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 1, characterized in that: It also includes a polarization-maintaining fiber wavelength division multiplexer, which is used to input the pump laser into the polarization-maintaining fiber coupler. The polarization-maintaining fiber wavelength division multiplexer is provided with a first reflection end and a second reflection end. The first reflection end is connected to the pump laser, and the second reflection end is connected to the polarization-maintaining fiber coupler.

3. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 2, characterized in that: The polarization-maintaining fiber coupler is provided with a first port, a second port, a third port and a fourth port, and the dual phase shifter is provided with a first port and a second port; the first port is connected to the second reflection end, the second port is connected to the first port through the polarization-maintaining gain fiber, the second port is connected to the third port, and the fourth port is connected to the output device.

4. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 3, characterized in that: The dual phase shifter includes a first polarization-maintaining fiber collimator, a second polarization-maintaining fiber collimator, a polarization beam splitter, a first Faraday rotator, a second Faraday rotator, a first wave plate, a second wave plate, a first reflector, and a second reflector; light transmitted on the slow axis of the first polarization-maintaining fiber collimator is transmitted through the polarization beam splitter prism and then reflected by the first Faraday rotator, the first wave plate, and the first reflector in sequence, the reflected light returns along the original optical path and passes through the first wave plate and the first Faraday rotator again, is reflected by the polarization beam splitter prism, and is received by the slow axis of the second polarization-maintaining fiber collimator; light transmitted on the fast axis of the first polarization-maintaining fiber collimator is reflected through the polarization beam splitter prism and then is reflected by the second Faraday rotator, the second wave plate, and the second reflector in sequence, the reflected light passes through the second wave plate and the second Faraday rotator in sequence, is transmitted by the polarization beam splitter prism, and the light transmitted through the beam splitter prism is received by the fast axis of the second polarization-maintaining fiber collimator; Among them, the dual phase shifter is used to simultaneously construct nonlinear amplification loop reflectors on the fast and slow axes of the polarization-maintaining optical fiber. The positions of the first reflector and the second reflector respectively determine the repetition frequencies of the two optical frequency combs. Moving the corresponding reflectors along the propagation direction of the light can independently adjust the repetition frequencies of the respective optical frequency combs.

5. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 4, characterized in that: The slow axis or the fast axis of the first polarization-maintaining fiber collimator is rotated 90 degrees relative to the slow axis or the fast axis of the second polarization-maintaining fiber collimator to ensure that light is always transmitted along the slow axis or the fast axis.

6. The single-resonant-cavity dual-optical frequency comb light source based on dual phase shifters according to claim 4, characterized in that: The first Faraday rotator and the second Faraday rotator rotate the incident linear polarization light by 45 degrees in the same direction.

7. The single-resonant cavity dual-optical frequency comb light source based on dual phase shifters according to claim 4, characterized in that: The fast axes of the first wave plate and the second wave plate are 45° to the horizontal plane, and the fast axes of the first wave plate and the second wave plate are perpendicular to each other in space; or; The slow axes of the first wave plate and the second wave plate form an angle of 45° with the horizontal plane, and the slow axis of the first wave plate and the slow axis of the second wave plate are perpendicular to each other in space.

8. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 1, characterized in that: The polarization-maintaining gain optical fiber adopts polarization-maintaining erbium-doped optical fiber or polarization-maintaining ytterbium-doped optical fiber.

9. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 1, characterized in that: The output device adopts a polarization-maintaining optical fiber that is half-reflective and half-mirror. The polarization-maintaining optical fiber that is half-reflective and half-mirror serves as an end mirror of the laser resonant cavity and outputs a dual optical frequency comb.

10. The single-resonance cavity dual-optical frequency comb light source based on dual phase shifters according to claim 1, characterized in that: The output device also includes a grating device for performing dispersion compensation on the laser resonant cavity.

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