Optical frequency comb generation device and method based on cross-polarization phase modulation

Abstract

The invention discloses an optical frequency comb generation device and method based on cross-polarization phase modulation, and relates to the technical field of optics. The device comprises a first light source, a second light source, a dual-polarization controller, an optical coupler, a nonlinear optical medium and a polarization beam splitter, the dual-polarization controller adjusts the polarization state of the tunable repetition-frequency pulse light provided by the first light source and the polarization state of the continuous single-frequency detection light provided by the second light source to be in a mutually orthogonal state, and the polarization states are coupled through the optical coupler. And the nonlinear optical medium performs cross phase modulation on the repetition-frequency pulse light and the single-frequency detection light in the coupled and cross-polarization state to form target pulse light and a target optical frequency comb in the coupled state, and the target pulse light and the target optical frequency comb are separated and output through the polarization beam splitter. Thus, the four-wave mixing effect between the pulsed light and the probe light can be eliminated, the optical comb with the adjustable frequency spacing is generated under the condition that the pulsed light and the probe light share the same central wavelength, comb teeth can be further expanded outwards, and therefore the effective spectral range of the optical frequency comb is widened.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to a light frequency comb generation device and method based on orthogonal polarization phase modulation. BACKGROUND

[0002] The light frequency comb is a kind of multi-wavelength light source with equal frequency interval and phase locking, which has important application in precise ranging, optical communication, microwave photonics and optical computing. Generally speaking, the light frequency comb can be realized by cavity structure scheme or cavity-free structure scheme. Among them, the cavity preparation scheme usually adopts mode-locked laser and nonlinear microcavity to obtain light frequency comb through cyclic frequency shift, but this scheme is limited by the inherent relationship between cavity length and light comb frequency interval, and cannot change the comb frequency interval of light frequency comb. Although the cavity-free preparation scheme usually adopts cascaded electro-optic modulator to obtain light frequency comb, it can realize flexible regulation of light comb frequency interval, but it is limited by the electrical bandwidth of radio frequency equipment and device, and the generated light frequency interval is usually not more than 50GHz, which cannot load high-speed signals in optical communication application, seriously restricting the communication capacity. SUMMARY

[0003] The main purpose of the present application is to provide a light frequency comb generation device and method based on orthogonal polarization phase modulation, aiming at solving the technical problem of how to improve the effective spectral range of light frequency comb.

[0004] To achieve the above-mentioned purpose, the embodiment of the present application provides a light frequency comb generation device based on orthogonal polarization phase modulation, which comprises: A first light source for providing a repetitive frequency pulse light; A second light source for providing a single frequency probe light; A dual polarization controller for receiving the repetitive frequency pulse light and the single frequency probe light, and adjusting and maintaining the polarization state of the repetitive frequency pulse light and the single frequency probe light as orthogonal polarization state; An optical coupler for coupling the repetitive frequency pulse light and the single frequency probe light in orthogonal polarization state, and transmitting the coupled repetitive frequency pulse light and the single frequency probe light to a nonlinear optical medium; The nonlinear optical medium is used for cross phase modulation of the repetitive frequency pulse light and the single frequency probe light in coupling state based on Kerr nonlinear effect, to form target pulse light and target light frequency comb in coupling state; A polarization beam splitter for separating and outputting the target light frequency comb from the target pulse light and the target light frequency comb in coupling state.

[0005] In one embodiment, the center wavelength of the repetition rate pulse light is the same as that of the single-frequency probe light, and the tooth spacing of the target optical frequency comb is equal to the repetition frequency of the repetition rate pulse light.

[0006] In one embodiment, the nonlinear optical medium includes any one of highly nonlinear optical fiber, silicon nitride waveguide, indium phosphide waveguide, lithium niobate waveguide, and aluminum gallium arsenide waveguide.

[0007] In one embodiment, the polarization beam splitter includes any one of an optical fiber polarization beam splitter and a silicon on-chip polarization beam splitter.

[0008] In one embodiment, the dual polarization controller includes: a first polarization controller and a second polarization controller; The first polarization controller is used to adjust the polarization state of the repetition rate pulse light so that the polarization state of the repetition rate pulse light is consistent with the fast axis or transverse magnetic mode direction of the nonlinear optical medium. The second polarization controller is used to adjust the polarization state of the single-frequency probe light so that the polarization state of the single-frequency probe light is consistent with the slow axis or transverse electric mode direction of the nonlinear optical medium.

[0009] In one embodiment, the optical frequency comb generating device further includes: an optical power amplifier; The optical power amplifier is used to adjust the peak power of the repetition rate pulse light to a preset peak power, and to provide the repetition rate pulse light with the preset peak power to the dual polarization controller.

[0010] In one embodiment, the optical frequency comb generating device further includes: a dispersive element; The dispersive element is used to multiply the repetition frequency of the repetition pulse light to a preset frequency based on the time-domain Talbot effect, and to provide the repetition pulse light of the preset frequency to the dual polarization controller.

[0011] Furthermore, this application also proposes a method for generating an optical frequency comb based on orthogonal polarization phase modulation, applied to the optical frequency comb generating device described above. The steps of the optical frequency comb generating method include: Provides high-repetition-rate pulsed light; Provides single-frequency probe light; The polarization states of the repetition rate pulse light and the single-frequency probe light are adjusted and maintained in an orthogonal polarization state by a dual polarization controller; The repetition-rate pulse light and the single-frequency probe light, which are in an orthogonal polarization state, are coupled by an optical coupler; Using a nonlinear optical medium, based on the Kerr nonlinear effect, cross-phase modulation is performed on the repetition rate pulse light and the single-frequency probe light in a coupled state to form a target pulse light and a target optical frequency comb in a coupled state. The target pulse light and the target optical frequency comb, which are in a coupled state, are separated by a polarization beam splitter, and the target optical frequency comb is output.

[0012] In one embodiment, before the step of adjusting and maintaining the polarization states of the repetition rate pulse light and the single-frequency probe light to an orthogonal polarization state using a dual polarization controller, the method further includes: The peak power of the repetition rate pulse light is adjusted to a preset peak power by a power amplifier, and the repetition rate pulse light with the preset peak power is provided to the dual polarization controller.

[0013] In one embodiment, before the step of adjusting and maintaining the polarization states of the repetition rate pulse light and the single-frequency probe light to an orthogonal polarization state using a dual polarization controller, the method further includes: By using a dispersive element based on the time-domain Talbot effect, the repetition frequency of the repetition pulse light is multiplied to a preset frequency, and the repetition pulse light of the preset frequency is provided to the dual polarization controller.

[0014] This application provides an optical frequency comb generation device and method based on orthogonal polarization phase modulation. The optical frequency comb generation device includes: a first light source, a second light source, a dual polarization controller, an optical coupler, a nonlinear optical medium, and a polarization beam splitter. The dual polarization controller adjusts the polarization states of tunable repetition-frequency pulse light provided by the first light source and continuous single-frequency probe light provided by the second light source to maintain mutual orthogonality, and couples them through the optical coupler. Subsequently, the nonlinear optical medium can perform cross-phase modulation on the coupled and orthogonally polarized repetition-frequency pulse light and single-frequency probe light to form a coupled target pulse light and a target optical frequency comb, which are then separated and output through the polarization beam splitter. Through the above design, the four-wave mixing effect between the pulse light and the probe light can be eliminated. When the pulse light and the probe light have the same center wavelength, an optical comb with adjustable frequency spacing is generated, and the comb teeth can be further expanded outward, thereby improving the effective spectral range of the optical frequency comb. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a schematic diagram of the structure of the optical frequency comb generation device based on orthogonal polarization phase modulation provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the time-domain waveforms of two types of light transmitted in the nonlinear optical medium of this application; Figure 3 This is a schematic diagram of the spectrum of the optical frequency comb targeted in this application; Figure 4 This is a schematic diagram of the structure of the optical frequency comb generation device based on orthogonal polarization phase modulation provided in Embodiment 2 of this application; Figure 5 This is a schematic diagram of the structure of the optical frequency comb generation device based on orthogonal polarization phase modulation provided in Embodiment 3 of this application; Figure 6 This is a flowchart illustrating an embodiment of the optical frequency comb generation method based on orthogonal polarization phase modulation provided in this application; Figure 7 This is a flowchart illustrating Embodiment 2 of the optical frequency comb generation method based on orthogonal polarization phase modulation provided in this application; Figure 8 This is a flowchart illustrating Embodiment 3 of the optical frequency comb generation method based on orthogonal polarization phase modulation provided in this application.

[0018] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0020] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0021] It should be understood that in the actual application of optical communication, the design of optical frequency combs is often forced to set wavelength guard intervals because the same polarization high peak pump and probe light will induce four-wave mixing idler sidebands under phase matching conditions, and the spectral broadening overlaps due to self-phase modulation effect, resulting in a double compression of the effective number of comb teeth and the total bandwidth.

[0022] Based on the aforementioned technical problems objectively existing in optical communication applications, this application proposes a first embodiment of an optical frequency comb generation device based on orthogonal polarization phase modulation. Please refer to... Figure 1 , Figure 2 as well as Figure 3 The optical frequency comb generating device includes: First light source 1, used to provide high-repetition-rate pulsed light; Second light source 2, used to provide single-frequency detection light; A dual polarization controller 45 is used to receive the repetition rate pulse light and the single-frequency probe light, and to adjust and maintain the polarization state of the repetition rate pulse light and the single-frequency probe light as orthogonal polarization. Optical coupler 6 is used to couple the repetition-rate pulse light and the single-frequency probe light, which are in orthogonal polarization, and to transmit the coupled repetition-rate pulse light and single-frequency probe light to the nonlinear optical medium 7; The nonlinear optical medium 7 is used to perform cross-phase modulation on the repetition rate pulse light and the single-frequency probe light in a coupled state based on the Kerr nonlinear effect, to form a target pulse light and a target optical frequency comb in a coupled state. The polarization beam splitter 8 is used to separate the target pulse light and the target optical frequency comb that are in a coupled state and output the target optical frequency comb.

[0023] It should be understood that, in this embodiment, the first light source 1 can specifically be a gain-switched laser, which can output pump light with a repetition frequency and a specific pulse width, i.e., the aforementioned high-repetition-rate pulse light; the second light source 2 can specifically be a narrow-linewidth external cavity laser, which can output single-frequency and continuous probe light, i.e., the aforementioned single-frequency probe light, which is mainly used to provide a seed light source for the target optical frequency comb to be explained later.

[0024] It is worth noting that, in this embodiment, the center wavelength of the single-frequency probe light can be arbitrarily selected.

[0025] It should be noted that, in this embodiment, the dual polarization controller 45 refers to a device for changing the polarization state of a light beam. It has two transmission channels, one for the aforementioned repetition-rate pulse light and the other for the aforementioned single-frequency probe light. Its main functions are to adjust the polarization states of the repetition-rate pulse light and the single-frequency probe light, respectively, so that the repetition-rate pulse light and the single-frequency probe light form and maintain orthogonal polarization. This cuts off the phase matching condition of the aforementioned four-wave mixing, preventing crosstalk between the repetition-rate pulse light and the single-frequency probe light.

[0026] It is easy to understand that the optical coupler 6 is mainly used to couple two beams of light with different polarization states. In this embodiment, the optical coupler 6 can couple the repetitive pulse light and the single-frequency probe light while maintaining orthogonal polarization, so as to provide a common transmission channel for subsequent synchronous entry into the nonlinear medium.

[0027] It should be noted that the Kerr nonlinear effect refers to the linear relationship between the refractive index of a material and the instantaneous change in light intensity. In this embodiment, the nonlinear optical medium 7 is an optical device with a high nonlinear coefficient γ and polarization-maintaining characteristics. It can maintain the orthogonal polarization state between the repetitive pulse light and the single-frequency probe light, and can utilize the Kerr nonlinear effect to make the repetitive pulse light (pump pulse) in the coupled state generate periodic cross-phase modulation on the single-frequency probe light, thereby converting the single-frequency continuous wave of the single-frequency probe light into a target optical frequency comb with an unchanged center wavelength.

[0028] It should be understood that an optical frequency comb refers to a "frequency scale" composed of several equally spaced, phase-locked narrow linewidth laser spectral lines, which appear as a series of uniformly distributed peaks in the spectrum. The frequency difference between two adjacent peaks is the comb tooth spacing. In this embodiment, the target optical frequency comb refers to an optical frequency comb with the required comb tooth spacing, phase, and other optical parameters formed after orthogonal phase modulation.

[0029] It is worth noting that the target pulse light refers to the pulse light formed after orthogonal phase modulation. In this embodiment, during the relatively long phase modulation process of the nonlinear optical medium 7, part of the peak power of the original repetition rate pulse light is consumed by using it to modulate the phase of the single-frequency probe light. At the same time, the pulse light spectrum is broadened due to the self-phase modulation effect, ultimately forming the corresponding target pulse light. However, compared to the repetition rate pulse light after polarization state adjustment, the center wavelength, repetition frequency, pulse width, and polarization state of the target pulse light remain basically unchanged.

[0030] It is easy to understand that the polarization beam splitter 8 is mainly used to separate and output orthogonally polarized input light based on its polarization state. In this embodiment, the polarization beam splitter 8 can separate the target pulse light and the target optical frequency comb output from the nonlinear optical medium 7, which are in a coupled state, with different polarization states, and output them separately through one optical transmission channel.

[0031] Furthermore, in this embodiment, the center wavelength of the repetition rate pulse light is the same as that of the single-frequency detection light, and the tooth spacing of the target optical frequency comb is equal to the repetition frequency of the repetition rate pulse light.

[0032] It should be noted that in this embodiment, since the dual polarization controller 45 adjusts the polarization state of the repetition-rate pulse light and the single-frequency probe light to an orthogonal polarization state, this embodiment does not need to set a protection bandwidth for them, allowing the center wavelengths of the repetition-rate pulse light and the single-frequency probe light to be set to the same value. Thus, the aforementioned eliminated protection bandwidth can be used as available bandwidth, allowing the comb teeth to expand further outward, thereby further improving the effective spectral range. Ultimately, a wide-spectrum, wide-spacing optical frequency comb light source can be obtained.

[0033] It is easy to understand that, in this embodiment, the repetition frequency of the repetition rate pulse light (pump pulse) can be understood as the phase modulation period corresponding to the single-frequency probe light in cross-phase modulation. Therefore, after Fourier transform, the probe spectrum of the single-frequency probe light changes from a single delta line to multiple delta lines spaced at intervals corresponding to the aforementioned repetition frequency. The spacing between the comb teeth of the optical frequency comb can automatically lock the repetition frequency of the repetition rate pulse light without the need for additional phase-locking or filters. Here, "delta line" refers to the Dirac delta function, used to represent the peaks corresponding to the aforementioned comb teeth.

[0034] It is worth noting that in this embodiment, the center wavelengths of the repetition rate pulse light and the single-frequency probe light are set to be the same, thereby saving the originally required protection bandwidth. Furthermore, by ensuring that the spacing between the comb teeth of the target optical frequency comb is equal to the repetition frequency of the repetition rate pulse light, the previously wasted frequency band can be converted into equidistant, usable comb teeth without idle frequencies, thereby further improving the effective spectral range.

[0035] like Figure 2 as well as Figure 3 As shown, Figure 2 This describes the time-domain waveform diagrams of two types of light propagating in the nonlinear optical medium 7, namely, the time-domain relationship between the repetitive pulse light (target pulse light) and the single-frequency probe light in orthogonal polarization state propagating in the nonlinear optical medium 7. Figure 3 This describes a schematic diagram of the spectrum of the target optical frequency comb. Among them, This represents the original repetition period of the high-repetition-rate pulse light; This is the original repetition frequency of the high-repetition-rate pulse light; The full width at half maximum (FWHM) of the high-repetition-rate pulse light; The time-domain Tuber multiplication factor (a positive integer) represents the number of times the pulse sequence is replicated within one period. This mainly corresponds to the technical scenario of subsequently setting the dispersive element 9. Since the dispersive element 9 is not set in this embodiment, it can be understood as... =1; This is the new repetition frequency after being multiplied by the Taber effect; The center frequency of the single-frequency probe light.

[0036] Furthermore, in this embodiment, the nonlinear optical medium 7 includes any one of the following: highly nonlinear optical fiber, silicon nitride waveguide, indium phosphide waveguide, lithium niobate waveguide, and aluminum gallium arsenide waveguide.

[0037] It is easy to understand that in this embodiment, the nonlinear optical medium 7 only needs to have polarization-maintaining characteristics and a sufficiently high nonlinear coefficient γ; the specific material or manufacturing process of the nonlinear optical medium 7 is not limited here. As a preferred embodiment, it can be any one of the following: highly nonlinear optical fiber, silicon nitride waveguide, indium phosphide waveguide, lithium niobate waveguide, and aluminum gallium arsenide waveguide.

[0038] Furthermore, in this embodiment, the polarization beam splitter 8 includes any one of an optical fiber polarization beam splitter and a silicon substrate polarization beam splitter.

[0039] It is easy to understand that in this embodiment, the polarization beam splitter 8 only needs to be able to split two orthogonally polarized beams into two output beams according to their polarization direction; the specific material or manufacturing process of the polarization beam splitter 8 is not limited here. As a preferred embodiment, the polarization beam splitter 8 can be a fiber polarization beam splitter, which has the characteristics of low insertion loss and easy splicing; as another preferred embodiment, the polarization beam splitter 8 can also be a silicon substrate polarization beam splitter, which has the characteristics of small size, mass production capability, and easy integration.

[0040] It is worth noting that, in this embodiment, the polarization beam splitter 8 should also have a high extinction ratio to reduce crosstalk between the target pulse light and the target optical frequency comb, thereby achieving lossless and high-purity polarization separation.

[0041] Furthermore, in this embodiment, the dual polarization controller 45 includes: a first polarization controller 4 and a second polarization controller 5; The first polarization controller 4 is used to adjust the polarization state of the repetition pulse light so that the polarization state of the repetition pulse light is consistent with the fast axis or transverse magnetic mode direction of the nonlinear optical medium 7. The second polarization controller 5 is used to adjust the polarization state of the single-frequency probe light so that the polarization state of the single-frequency probe light is consistent with the slow axis or transverse electric mode direction of the nonlinear optical medium 7.

[0042] It should be noted that, in this embodiment, the geometric symmetry of the nonlinear optical medium 7 leads to different propagation speeds of light in two orthogonally polarized states. The fast axis or transverse magnetic mode (TM mode) direction refers to the polarization direction with a low refractive index and high light speed, while the slow axis or transverse electric mode (TE mode) direction refers to the polarization direction with a high refractive index and slow light speed. Only when the two polarization states of the input orthogonal light are incident along the fast axis (TM mode) / slow axis (TE mode) directions respectively can the two beams maintain a strictly 90° orthogonal polarization state and a constant group velocity difference, ensuring that the polarization state remains unchanged throughout the entire path (i.e., the aforementioned polarization-preserving characteristic), thus disrupting the phase matching of the four-wave mixing and facilitating 100% separation.

[0043] It is readily understood that in this embodiment, the dual polarization controller 45 can consist of an independent first polarization controller 4 and an independent second polarization controller 5. The first polarization controller 4 adjusts the polarization state of the repetitive pulse light to align it with the fast axis or transverse magnetic mode (TM mode) direction of the subsequently configured nonlinear optical medium 7. Correspondingly, the second polarization controller 5 adjusts the polarization state of the single-frequency probe light to align it with the slow axis or transverse electric mode (TE mode) direction of the subsequently configured nonlinear optical medium 7. Based on this coordination, orthogonal polarization co-path transmission can be achieved, eliminating the need for a guard band.

[0044] As a preferred method, such as Figure 3 As shown, the polarization state of the adjusted single-frequency probe light is X-polarized, and the polarization state of the adjusted repetition pulse light is Y-polarized.

[0045] This application proposes an optical frequency comb generation device based on orthogonal polarization phase modulation. The device includes a first light source, a second light source, a dual polarization controller, an optical coupler, a nonlinear optical medium, and a polarization beam splitter. The dual polarization controller adjusts the polarization states of tunable repetition-rate pulse light from the first light source and continuous single-frequency probe light from the second light source to maintain mutual orthogonality, and couples them through the optical coupler. Subsequently, the nonlinear optical medium performs cross-phase modulation on the coupled and orthogonally polarized repetition-rate pulse light and single-frequency probe light to form a coupled target pulse light and a target optical frequency comb, which are then separated and output through the polarization beam splitter. This design eliminates the four-wave mixing effect between the pulse light and the probe light. With the pulse light and probe light having the same center wavelength, an optical comb with adjustable frequency spacing is generated, and the comb teeth can be further expanded outwards, thereby improving the effective spectral range of the optical frequency comb.

[0046] Based on the first embodiment of the optical frequency comb generating device based on orthogonal polarization phase modulation of this application, in the second embodiment of the optical frequency comb generating device based on orthogonal polarization phase modulation of this application, the contents that are the same as or similar to those in the first embodiment can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 4 In this embodiment, the optical frequency comb generating device further includes: an optical power amplifier 3; The optical power amplifier 3 is used to adjust the peak power of the repetition rate pulse light to a preset peak power, and to provide the repetition rate pulse light with the preset peak power to the dual polarization controller.

[0047] It should be noted that the optical power amplifier 3 is an optical device that can amplify the peak power of the repetitive pulse light. In this embodiment, the optical power amplifier 3 can be placed between the dual polarization controller and the first light source 1, thereby increasing the peak power of the repetitive pulse light output from the first light source 1 to the preset peak power required, and then providing the repetitive pulse light with the preset peak power to the dual polarization controller, thereby ensuring that the depth of subsequent cross-phase modulation is sufficient, and thus ensuring that the number of comb teeth and energy efficiency of the optical frequency comb meet the standards.

[0048] Based on the first embodiment of the optical frequency comb generating device based on orthogonal polarization phase modulation of this application, in the third embodiment of the optical frequency comb generating device based on orthogonal polarization phase modulation of this application, the content that is the same as or similar to that in the first embodiment can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 5 In this embodiment, the optical frequency comb generating device further includes: a dispersive element 9; The dispersive element 9 is used to multiply the repetition frequency of the repetition pulse light to a preset frequency based on the time-domain Talbot effect, and to provide the repetition pulse light of the preset frequency to the dual polarization controller.

[0049] It should be understood that the time-domain Talbot effect refers to the phenomenon where a short pulse sequence with a specific period is introduced into a dispersive medium, and when the group velocity dispersion of the dispersive medium meets certain conditions, the original pulse can be replicated at equal intervals. The formation cycle is shortened to [number] portions. A new pulse sequence.

[0050] It should be noted that the dispersive element 9 can be understood as a dielectric element with a specific wavelength / dispersion. In this embodiment, it can be combined with... Figure 2 as well as Figure 3 To understand this, the dispersive element 9 can be positioned between the dual polarization controller and the first light source 1. The "time-domain Talbot effect" of the dispersive element 9 can be used to determine the original repetition frequency of the high-repetition-rate pulse light output from the first light source 1. Doubled to demand This is the preset frequency mentioned above. Subsequently, the repetition rate pulse light at the preset frequency is transmitted to the dual polarization controller. In this way, without replacing the first light source 1, the tooth spacing of the final output target light comb can be adjusted from the original repetition frequency. Doubled to demand .

[0051] It is worth noting that, in this embodiment, as Figure 4 The optical power amplifier 3 shown and as shown Figure 5The dispersive element 9 shown can be simultaneously disposed in the optical frequency comb generating device proposed in this embodiment, so that the optical frequency comb generating device can simultaneously achieve the technical effects brought by the above two optical elements / devices.

[0052] This application also provides a method for generating an optical frequency comb based on orthogonal polarization phase modulation, applicable to the optical frequency comb generating apparatus described above. Please refer to... Figure 6 The optical frequency comb generation method includes steps S10 to S60: Step S10: Provide high-repetition-rate pulsed light; Step S20: Provide a single-frequency probe light; It should be understood that, in this embodiment, the executing entity is the optical frequency comb generating device described above.

[0053] It is easy to understand that in this embodiment, a repetition frequency pulse light with a tunable original repetition frequency can be provided by a first light source, while a continuous single-frequency probe light can be provided by a second light source.

[0054] Step S30: The polarization states of the repetition rate pulse light and the single-frequency probe light are adjusted and maintained as orthogonal polarization states by a dual polarization controller; Step S40: The repetition rate pulse light and the single-frequency probe light, which are in an orthogonal polarization state, are coupled together by an optical coupler; It is readily understood that, in this embodiment, the aforementioned high-repetition-rate pulse light and the aforementioned single-frequency probe light can be received separately by a dual polarization controller, and their polarization states can be adjusted and maintained as orthogonal polarization states that do not interfere with each other. Subsequently, they are coupled to the same optical transmission channel for transmission via an optical coupler.

[0055] It is worth noting that the optical coupler can also maintain the orthogonal polarization state between the repetitive pulse light and the single-frequency probe light.

[0056] Step S50: Using a nonlinear optical medium, based on the Kerr nonlinear effect, cross-phase modulation is performed on the repetition rate pulse light and the single-frequency probe light in the coupled state to form a target pulse light and a target optical frequency comb in the coupled state. Step S60: The target pulse light and the target optical frequency comb, which are in a coupled state, are separated by a polarization beam splitter and the target optical frequency comb is output.

[0057] It is readily understood that in this embodiment, the repetitive pulse light and the aforementioned single-frequency probe light, which are in a coupled and orthogonally polarized state, can be cross-phase modulated based on the Kerr nonlinear effect using a nonlinear optical medium. This results in the formation of a target optical frequency comb and a target pulse light that maintain orthogonal polarization in the same optical path. Subsequently, a polarization beam splitter can be used to separate and output the two light according to their respective polarization states. Through the steps of the optical frequency comb generation method proposed in this embodiment, the spectral utilization rate of the formed target optical frequency comb can be improved.

[0058] This application proposes a method for generating an optical frequency comb based on orthogonal polarization phase modulation. The method includes: adjusting the polarization states of a tunable repetition-rate pulse light from a first light source and a continuous single-frequency probe light from a second light source to maintain mutual orthogonality using a dual polarization controller, and coupling them via an optical coupler. Subsequently, the coupled and orthogonally polarized repetition-rate pulse light and single-frequency probe light are cross-phase modulated using a nonlinear optical medium to form a coupled target pulse light and a target optical frequency comb, which are then separated and output using a polarization beam splitter. This design eliminates the four-wave mixing effect between the pulse light and the probe light, generating an optical comb with adjustable frequency spacing when the pulse light and probe light have the same center wavelength. Furthermore, the comb teeth can be further expanded outwards, thereby improving the effective spectral range of the optical frequency comb.

[0059] Based on the first embodiment of the optical frequency comb generation method based on orthogonal polarization phase modulation of this application, in the second embodiment of the same or similar content as the first embodiment, please refer to the above description, and it will not be repeated hereafter. Based on this, please refer to... Figure 7 In this embodiment, before the step of adjusting and maintaining the polarization states of the repetition rate pulse light and the single-frequency probe light as orthogonal polarization using a dual polarization controller, the method further includes: Step S301: The peak power of the repetition rate pulse light is adjusted to a preset peak power through a power amplifier, and the repetition rate pulse light with the preset peak power is provided to the dual polarization controller.

[0060] It is easy to understand that, in this embodiment, the peak power of the repetition pulse light output by the first light source can be increased to the preset peak power required by the optical power amplifier set between the dual polarization controller and the first light source, and then the repetition pulse light with the preset peak power can be provided to the dual polarization controller, thereby ensuring that the depth of subsequent cross-phase modulation is sufficient, and thus ensuring that the number of comb teeth and energy efficiency of the optical frequency comb meet the standards.

[0061] Based on the first embodiment of the optical frequency comb generation method based on orthogonal polarization phase modulation of this application, in the third embodiment of the same or similar content as the first embodiment, please refer to the above description, and it will not be repeated hereafter. Based on this, please refer to... Figure 8 In this embodiment, before the step of adjusting and maintaining the polarization states of the repetition rate pulse light and the single-frequency probe light as orthogonal polarization using a dual polarization controller, the method further includes: Step S302: Using a dispersive element, based on the time-domain Talbot effect, the repetition frequency of the repetition pulse light is multiplied to a preset frequency, and the repetition pulse light of the preset frequency is provided to the dual polarization controller.

[0062] It is readily understood that, in this embodiment, a dispersive element disposed between the polarization controller and the first light source can be used to determine the original repetition frequency of the repetition pulse light output by the first light source through the "time-domain Talbot effect". Doubled to demand This is the preset frequency mentioned above. Subsequently, the repetition rate pulse light at the preset frequency is transmitted to the dual polarization controller. In this way, without changing the first light source, the tooth spacing of the final output target light comb can be adjusted from the original repetition frequency. Doubled to demand

[0063] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. An optical frequency comb generation device based on orthogonal polarization phase modulation, characterized in that, The optical frequency comb generating device includes: The first light source is used to provide high-repetition-rate pulsed light; The second light source is used to provide single-frequency detection light; A dual polarization controller is used to receive the repetition rate pulse light and the single-frequency probe light, and to adjust and maintain the polarization state of the repetition rate pulse light and the single-frequency probe light in an orthogonal polarization state; An optical coupler is used to couple the repetition-rate pulse light and the single-frequency probe light, which are in an orthogonal polarization state, and to transmit the coupled repetition-rate pulse light and the single-frequency probe light to a nonlinear optical medium; The nonlinear optical medium is used to perform cross-phase modulation on the repetition rate pulse light and the single-frequency probe light in a coupled state based on the Kerr nonlinear effect, to form a target pulse light and a target optical frequency comb in a coupled state. A polarization beam splitter is used to separate the target pulse light and the target optical frequency comb that are in a coupled state and output the target optical frequency comb.

2. The optical frequency comb generating apparatus as described in claim 1, characterized in that, The center wavelength of the repetition rate pulse light is the same as that of the single-frequency probe light, and the spacing between the comb teeth of the target optical frequency comb is equal to the repetition frequency of the repetition rate pulse light.

3. The optical frequency comb generating apparatus as described in claim 1, characterized in that, The nonlinear optical medium includes any one of the following: highly nonlinear optical fiber, silicon nitride waveguide, indium phosphide waveguide, lithium niobate waveguide, and aluminum gallium arsenide waveguide.

4. The optical frequency comb generating apparatus as described in claim 1, characterized in that, The polarization beam splitter includes any one of fiber polarization beam splitter and silicon on-chip polarization beam splitter.

5. The optical frequency comb generating apparatus as described in claim 1, characterized in that, The dual polarization controller includes: a first polarization controller and a second polarization controller; The first polarization controller is used to adjust the polarization state of the repetition rate pulse light so that the polarization state of the repetition rate pulse light is consistent with the fast axis or transverse magnetic mode direction of the nonlinear optical medium. The second polarization controller is used to adjust the polarization state of the single-frequency probe light so that the polarization state of the single-frequency probe light is consistent with the slow axis or transverse electric mode direction of the nonlinear optical medium.

6. The optical frequency comb generating apparatus according to any one of claims 1-5, characterized in that, The optical frequency comb generating device further includes: an optical power amplifier; The optical power amplifier is used to adjust the peak power of the repetition rate pulse light to a preset peak power, and to provide the repetition rate pulse light with the preset peak power to the dual polarization controller.

7. The optical frequency comb generating apparatus according to any one of claims 1-5, characterized in that, The optical frequency comb generating device further includes: a dispersive element; The dispersive element is used to multiply the repetition frequency of the repetition pulse light to a preset frequency based on the time-domain Talbot effect, and to provide the repetition pulse light of the preset frequency to the dual polarization controller.

8. A method for generating an optical frequency comb based on orthogonal polarization phase modulation, characterized in that, The optical frequency comb generating apparatus as described in any one of claims 1 to 7, wherein the steps of the optical frequency comb generating method include: Provides high-repetition-rate pulsed light; Provides single-frequency probe light; The polarization states of the repetition rate pulse light and the single-frequency probe light are adjusted and maintained in an orthogonal polarization state by a dual polarization controller; The repetition-rate pulse light and the single-frequency probe light, which are in an orthogonal polarization state, are coupled by an optical coupler; Using a nonlinear optical medium, based on the Kerr nonlinear effect, cross-phase modulation is performed on the repetition rate pulse light and the single-frequency probe light in a coupled state to form a target pulse light and a target optical frequency comb in a coupled state. The target pulse light and the target optical frequency comb, which are in a coupled state, are separated by a polarization beam splitter, and the target optical frequency comb is output.

9. The optical frequency comb generation method as described in claim 8, characterized in that, Before the step of adjusting and maintaining the polarization states of the repetition rate pulse light and the single-frequency probe light in an orthogonal polarization state using a dual polarization controller, the method further includes: The peak power of the repetition rate pulse light is adjusted to a preset peak power by a power amplifier, and the repetition rate pulse light with the preset peak power is provided to the dual polarization controller.

10. The optical frequency comb generation method as described in claim 8, characterized in that, Before the step of adjusting and maintaining the polarization states of the repetition rate pulse light and the single-frequency probe light in an orthogonal polarization state using a dual polarization controller, the method further includes: By using a dispersive element based on the time-domain Talbot effect, the repetition frequency of the repetition pulse light is multiplied to a preset frequency, and the repetition pulse light of the preset frequency is provided to the dual polarization controller.

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