A method, apparatus and system for generating a flat electro-optic frequency comb

Abstract

The present application belongs to the technical field of optoelectronics, and particularly relates to a method, device and system for generating a flat electro-optic frequency comb, comprising: integrating a cascaded electro-optic phase modulator and an electro-optic amplitude modulator in a ring resonator in which an optical signal is transmitted; and applying radio frequency modulation signals to the electro-optic phase modulator and the electro-optic amplitude modulator, so that a flat electro-optic frequency comb can be obtained in the cavity; wherein the ring resonator is composed of an electro-optic medium doped with a gain material, or is composed of a fiber loop with an optical gain element, so that the optical signal produces a 3dB optical gain in the ring resonator for each transmission; and the modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation signals of the two modulators are all determined based on a 1 adjacent frequency mode power ratio. The method solves the technical problem of uneven comb teeth faced by conventional electro-optic frequency combs.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronics technology, and more specifically, relates to a method, apparatus and system for generating a flat electro-optic frequency comb. Background Technology

[0002] Optical frequency combs contain a series of equally spaced, phase-coherent discrete frequency components and have wide applications in optical communication, precision spectroscopy, and precision measurement. Conventional cavity-based electro-optic frequency combs generate a frequency comb with symmetrically distributed sidebands by applying electro-optic phase modulation within the cavity. However, the power of the comb teeth produced by this method exhibits exponential decay away from the central tooth, resulting in uneven power distribution and affecting the operating bandwidth and application range of the optical frequency comb. Therefore, developing a power-flat electro-optic frequency comb has significant research and application value. Summary of the Invention

[0003] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method, apparatus and system for generating a flat electro-optic frequency comb, the purpose of which is to solve the technical problem of uneven comb teeth faced by existing conventional electro-optic frequency combs.

[0004] To achieve the above objectives, according to one aspect of the present invention, a method for generating a flat electro-optic frequency comb is provided, comprising: integrating a cascaded electro-optic phase modulator and an electro-optic amplitude modulator within a ring resonant cavity transmitting an optical signal; applying radio frequency modulation signals to the electro-optic phase modulator and the electro-optic amplitude modulator respectively; and obtaining a flat electro-optic frequency comb within the micro-ring resonant cavity; wherein the ring resonant cavity is composed of an electro-optic dielectric doped with a gain material, or is composed of an optical fiber loop having optical gain elements, such that the optical signal generates an optical gain of 3dB per revolution within the ring resonant cavity;

[0005] The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined by the following method:

[0006] By utilizing an electro-optic phase modulator and an electro-optic amplitude modulator cascaded within a ring resonant cavity, along with optical gain, non-reciprocal coupling between photonic frequency modes is constructed. This allows for the determination of the relationship between the coupling coefficient between frequency modes and the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulation electrical signals. Based on this relationship, and the relationship between the power ratio of adjacent frequency modes and the coupling coefficient between frequency modes when the input light satisfies the ring resonant cavity resonance condition, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators are determined when the power ratio of adjacent frequency modes is 1.

[0007] Furthermore, the modulated electrical signal of electro-optic phase modulation Among them, V 01 The amplitude of V1, V1 represents the initial phase, and Ω represents the modulation frequency.

[0008] Furthermore, the modulated electrical signal of electro-optic amplitude modulation Among them, V DC For DC bias, V 02 The amplitude of V2, Ω represents the initial phase of V2, and Ω represents the modulation frequency.

[0009] Furthermore, the modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators satisfy the following:

[0010] β1 << 1, β2 << 1, power ratio of adjacent frequency modes Where γ is the linewidth of the ring resonator, and T R β1 is the time required for one cycle of optical signal transmission, a is the modulation depth of the electro-optic phase modulator, and β1 is the time required for one cycle of optical signal transmission. n and a n-1 Let i represent the amplitude of the nth-order frequency mode and the amplitude of the (n-1)th-order frequency mode, respectively, where i represents the imaginary unit and β represents the amplitude of the (n-1)th-order frequency mode. a The modulation depth of the electro-optic amplitude modulator, β2 = β a / 2, This represents the phase difference between the two modulated electrical signals.

[0011] further,

[0012] According to another aspect of the present invention, a flat electro-optic frequency comb generating device is provided, comprising: an input and output waveguides and a ring resonant cavity; the input and output waveguides are used for inputting and outputting optical signals, and the ring resonant cavity is composed of an electro-optic dielectric doped with gain material or an optical fiber loop having optical gain elements, wherein a cascaded electro-optic phase modulator and an electro-optic amplitude modulator are integrated therein for performing electro-optic phase modulation and electro-optic amplitude modulation on the optical signal coupled from the input and output waveguides, and generating an optical gain of 3dB for each revolution of the optical signal in the ring resonant cavity;

[0013] The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined by the following method:

[0014] By utilizing an electro-optic phase modulator and an electro-optic amplitude modulator cascaded within a ring resonant cavity, along with optical gain, non-reciprocal coupling between photonic frequency modes is constructed. This allows for the determination of the relationship between the coupling coefficient between frequency modes and the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulation electrical signals. Based on this relationship, and the relationship between the power ratio of adjacent frequency modes and the coupling coefficient between frequency modes when the input light satisfies the ring resonant cavity resonance condition, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators are determined when the power ratio of adjacent frequency modes is 1.

[0015] According to another aspect of the present invention, a flat electro-optic frequency comb generation system is provided, comprising: a flat electro-optic frequency comb generation device as described above, a single-frequency light source for inputting single-frequency light into the input and output waveguides in the generation device, a first radio frequency source for applying a first modulation electrical signal to a phase modulator integrated in a ring resonant cavity to achieve phase modulation; and a second radio frequency source for applying a second modulation electrical signal to an amplitude modulator integrated in the ring resonant cavity to achieve amplitude modulation.

[0016] In summary, compared with the prior art, the technical solutions conceived by this invention have the following main advantages:

[0017] 1. This invention proposes a method for generating a flat electro-optic frequency comb. The flat electro-optic frequency comb is generated based on a ring resonant cavity composed of an electro-optic dielectric doped with gain material, which integrates cascaded phase modulators and amplitude modulators. The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined based on the power ratio of adjacent frequency modes being 1. The entire generation method requires a simple device structure, which can be constructed through an optical fiber system or based on integrated optical devices to achieve on-chip integration. The generated electro-optic frequency comb has excellent power flatness, with comb tooth power variation within the range of 0-1.5dB, making it suitable for applications in precision measurement, optical communication, and other fields.

[0018] 2. The present invention further preferably provides the conditions for satisfying three parameters: the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators, which is simple and achieves an electro-optic frequency comb with good power flatness. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the generation structure of a flat electro-optic frequency comb provided in an embodiment of the present invention;

[0020] Figure 2 This is a graph showing the relationship between the power ratio L of adjacent frequency modes and the modulation depth β provided in an embodiment of the present invention.

[0021] Figure 3 This is a diagram showing the generation result of a flat electro-optic frequency comb provided in an embodiment of the present invention, wherein (a) is a simulation result diagram and (b) is a theoretical calculation result diagram. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Example 1

[0024] A method for generating a flat electro-optic frequency comb includes: integrating a cascaded electro-optic phase modulator and an electro-optic amplitude modulator within a ring resonant cavity transmitting an optical signal; applying radio frequency modulation signals to the electro-optic phase modulator and the electro-optic amplitude modulator respectively; and obtaining a flat electro-optic frequency comb within the micro-ring resonant cavity; wherein the ring resonant cavity is composed of an electro-optic dielectric doped with gain material, or is composed of an optical fiber loop with optical gain elements, such that the optical signal generates an optical gain of 3dB per revolution within the ring resonant cavity;

[0025] The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined by the following method:

[0026] By utilizing an electro-optic phase modulator and an electro-optic amplitude modulator cascaded within a ring resonant cavity, along with optical gain, non-reciprocal coupling between photonic frequency modes is constructed. This allows for the determination of the relationship between the coupling coefficient between frequency modes and the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulation electrical signals. Based on this relationship, and the relationship between the power ratio of adjacent frequency modes and the coupling coefficient between frequency modes when the input light satisfies the ring resonant cavity resonance condition, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators are determined when the power ratio of adjacent frequency modes is 1.

[0027] The frequency comb generated in this embodiment is a ring resonant cavity, and the frequency comb is generated by electro-optic modulation. The principle of generating a flat frequency comb is achieved by constructing non-reciprocal coupling between frequency modes. The optical gain in the ring resonant cavity is generated by the gain medium.

[0028] Structures used to generate flat electro-optic frequency combs, such as Figure 1 As shown, the ring resonant cavity simultaneously contains phase modulation, amplitude modulation, and optical gain.

[0029] The following analyzes the optical field modulation process experienced by the optical signal within the micro-ring resonant cavity: 1. Phase modulation: By applying a modulation electrical signal to a segment of the optical waveguide in the ring resonant cavity, the refractive index of this segment of the optical waveguide is dynamically modulated, thereby causing the optical signal passing through this segment of the optical waveguide to generate a time-varying phase. When the modulation electrical signal is... When (which can be used as a preferred phase modulation electrical signal), it is equivalent to generating a phase for the optical signal passing through this section of the optical waveguide, denoted as... Where Ω is the modulation frequency, and its value is equal to the free spectral range (FSR) of the ring resonator; β1 is the modulation depth of the phase modulation, β1 = Δnk0L0; Δn is the maximum amplitude of the refractive index change caused by the above dynamic modulation; k0 is the wave vector in vacuum; and L0 is the modulation length. This represents the phase of the modulated signal. After phase modulation, the transmission coefficient of this section of the optical waveguide... 2. Amplitude modulation (e.g., Mach-Zehnder interferometry (MZI) type amplitude modulation), when the modulating electrical signal is At that time, V DC For DC bias, V 02 The voltage amplitude is dynamically modulated, and the phase difference generated by the two arms of the amplitude modulation is... φ DC β is the phase difference generated between the two arms when a DC voltage is applied. a The modulation depth is the amplitude modulation depth. This represents the phase of the modulated signal. The transmission coefficient T of the optical signal after amplitude modulation is... MZI =cos(φ a / 2), without modulation, i.e., β a When φ = 0, DC =π / 2, so |T MZI | 2 =1 / 2; in β a When <<1, for cos(φ) a / 2) Performing a first-order Taylor expansion, we have:

[0030]

[0031] 3. The total transmittance coefficient T is expressed based on Equation 1 as follows:

[0032]

[0033] Let β2 = β a / 2 represents the modulation depth of a single arm of the MZI, and the coefficient This means that, based on the phase modulation and amplitude modulation mentioned above, the optical signal needs to pass through a gain medium to generate twice the optical gain for each transmission cycle.

[0034] For example, suppose the intrinsic loss rate of the ring resonator is γ in The external channel coupling rate is γ ex The total loss rate is γ = γ in +γ ex According to the time-domain coupled-mode theory, when the input is single-frequency light (frequency ω...) input ), and using the rotating wave approximation, the complex amplitude of the frequency mode of the ring resonator {a n The evolution equation for} is:

[0035]

[0036] Where n = 0, ..., N, represents the nth order frequency mode, and the coupling coefficient between frequency modes. It is the phase difference T between two modulated electrical signals. R This is the time required for a single loop (i.e., one complete transmission of the optical signal).

[0037] The input and output waveguide outputs are:

[0038]

[0039] When the input light satisfies the resonance condition of the ring resonator, the steady-state condition (da) is solved iteratively. n When / dt=0), Equation 2 relates to each frequency mode (a) N The equations leading to a0) specifically involve solving for the Nth frequency mode in steady-state equation 2, i.e.

[0040]

[0041] It can be obtained Then substitute the information about a N-1 The steady-state equation (Equation 2) is, i.e.

[0042]

[0043] achievable Continuing the above iterative process, the amplitude a of any n-order frequency mode under steady-state conditions can be obtained. n :

[0044]

[0045] Since N is very large, let Depend on and have to:

[0046]

[0047] Therefore, the amplitude relationship between any nth order frequency mode and the (n-1)th order frequency mode is: in The power ratio of adjacent frequency modes is expressed as: Because of t + and t - It is a function of modulation depths β1 and β2, therefore L is related to modulation depths β1 and β2. When the applied modulation signal has the form of... And when the modulation depth satisfies β1=β2=β, D=C, we can obtain: t + =2C,t - =0, f1=1. At this point, the relationship between L and β modulation depth is as follows: Figure 2 As shown by the solid line (in this invention), the diamond-shaped scatter plot represents the simulation results. Under small signal conditions (β1=β2=β<<1), the simulation and theoretical curves show good agreement, verifying the principle and theoretical model of this invention. As a preferred embodiment, let... have to At this point, all frequency modes have the same amplitude, thus enabling the generation of frequency combs with perfectly flat teeth, and the method is simple. It should be noted that, since C = β / 2T... R In order for equation 1 to hold (i.e., β) a <<1) Approximate condition needs to be met: β a =2β2=2β<<1, the linewidth γ should not be too large. The linewidth γ of the micro-ring resonator can be reduced by reducing waveguide scattering loss and external channel coupling rate.

[0048] Therefore, as a preferred embodiment, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulating electrical signals satisfy the following:

[0049] β1 << 1, β2 << 1, power ratio of adjacent frequency modes Where γ is the linewidth of the ring resonator, and T R β1 is the time required for one cycle of optical signal transmission, a is the modulation depth of the electro-optic phase modulator, and β1 is the time required for one cycle of optical signal transmission. n and a n-1 Let i represent the amplitude of the nth-order frequency mode and the amplitude of the (n-1)th-order frequency mode, respectively, where i represents the imaginary unit and β represents the amplitude of the (n-1)th-order frequency mode. a The modulation depth of the electro-optic amplitude modulator, β2 = β a / 2, This represents the phase difference between the two modulated electrical signals.

[0050] Further, as a preferred implementation method,

[0051] It should be noted that a single-input-output waveguide is used when inputting and outputting optical signals.

[0052] This embodiment introduces electro-optic phase modulation and electro-optic amplitude modulation components into a single-input / output waveguide-coupled microring resonator with electro-optic effect and optical gain. This theoretically constructs non-reciprocal coupling between intracavity frequency modes, and the conditions for achieving a flat electro-optic frequency comb are derived using time-domain coupled-mode theory. The modulation signal satisfies the condition: the phase difference between the modulation signals... Modulation depth β a When β = 2β2 << 1 and β1 = β2, the frequency comb generated by this method can theoretically achieve high flatness and high output power. In fact, any small-signal modulation satisfying L = 1 can generate a flat electro-optic frequency comb. The main purpose is to minimize the required modulation depths β1 and β2, which is simple and convenient.

[0053] This embodiment presents an on-chip integrated device for generating a flat electro-optic frequency comb, the structure of which is designed as follows: Figure 1 As shown, the microring resonant cavity integrates an electro-optic phase modulator and an MZI amplitude modulator. The MZI amplitude modulator is split into two beams by a 50:50 Y-branch, and then the two arms are electro-optically modulated by an electrical signal loaded through the GSG electrodes. Finally, the beams are combined through the Y-branch to form a push-pull MZI amplitude modulator. The overall microcavity structure is based on materials with electro-optic effects and optical gain, such as rare-earth-doped thin-film lithium niobate.

[0054] Example 2

[0055] A device for generating a flat electro-optic frequency comb includes: an input and output waveguides and a ring resonant cavity; the input and output waveguides are used for inputting and outputting optical signals, and the ring resonant cavity is composed of an electro-optic dielectric doped with gain material or an optical fiber loop with optical gain elements, wherein a cascaded electro-optic phase modulator and an electro-optic amplitude modulator are integrated therein for electro-optic phase modulation and electro-optic amplitude modulation of the optical signal coupled from the input and output waveguides, and for generating an optical gain of 3dB for each revolution of the optical signal in the ring resonant cavity;

[0056] The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined by the following method:

[0057] By utilizing an electro-optic phase modulator and an electro-optic amplitude modulator cascaded within a ring resonant cavity, along with optical gain, non-reciprocal coupling between photonic frequency modes is constructed. This allows for the determination of the relationship between the coupling coefficient between frequency modes and the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulation electrical signals. Based on this relationship, and the relationship between the power ratio of adjacent frequency modes and the coupling coefficient between frequency modes when the input light satisfies the ring resonant cavity resonance condition, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators are determined when the power ratio of adjacent frequency modes is 1.

[0058] The device for generating a flat electro-optic frequency comb can be designed according to the following process:

[0059] The working principle of realizing a flat electro-optic frequency comb is analyzed, and the structural parameters for generating the flat electro-optic frequency comb are theoretically designed and determined, including cavity length, power coupling coefficient between resonant cavity and input waveguide, modulation depth of phase modulator and amplitude modulator, and phase difference of modulation signals of the two modulators.

[0060] The theoretically designed structure and various parameters are set in the simulation software, and the simulation results are compared with the theoretical calculations to verify the principle and theoretical model.

[0061] The structure and parameters of the flat electro-optic frequency comb are set in the simulation software, and the steady-state spectrum of the output frequency comb, as well as the comb power, number of comb teeth, bandwidth and other parameters of the flat optical frequency comb are simulated and calculated.

[0062] For example, 1. Theoretical design determines the structural parameters for generating a flat electro-optic frequency comb.

[0063] First, the power coupling coefficient γ between the single-input / output waveguide and the micro-ring resonator is set. ex The FSR of the microring resonator is 2π*10GHz, the waveguide loss of the microring is 10dB / m, and the half-wave voltage of the phase modulator is 5V. The MZI-type amplitude modulator consists of two Y branches connected by two arms of equal length, each arm containing a phase modulator with a half-wave voltage of 5V. A -1.25V DC bias is applied to the upper arm, and a +1.25V DC bias is applied to the lower arm. The linewidth γ of the microcavity (excluding gain) can be theoretically calculated to be 2π*208.4MHz. Based on the above theoretical analysis, the modulation signal form for achieving a flat frequency comb satisfies β1 = β2. Make At that time, to determine the form of the modulation signal required to simulate and realize a flat optical frequency comb, γ in This represents the total waveguide loss of the microring.

[0064] 2. Simulation of on-chip flat electro-optic frequency comb

[0065] The theoretically designed structure and various parameters are set in the simulation software, and the spectrum of the output frequency comb is calculated through simulation. The simulation results are compared with the theoretical calculations to verify the principle and theoretical model.

[0066] 3. Performance Characterization of On-Chip Flat Electro-Optical Frequency Comb

[0067] The structure and parameters of the flat electro-optic frequency comb source are set in the simulation software, and the steady-state spectrum of the output frequency comb, as well as the comb power, number of comb teeth, bandwidth and other parameters of the flat optical frequency comb are simulated and calculated.

[0068] To calculate the performance parameters of the on-chip flat electro-optic frequency comb, simulation calculations were performed using optical simulation software following the steps outlined above. A resonant single-frequency optical input / output waveguide with a power of 0 dBm was selected. The modulation depth of the sinusoidal signal applied by the phase modulator was β1 = 0.0229π, and the modulation depth of the sinusoidal signal applied by a single arm of the amplitude modulator was β2 = 0.0229π (making D = C). Both arms were inversely modulated, and the frequencies of the modulation signals for both phase and amplitude modulation were equal to the FSR. The phase difference between the modulation signals was... Adjustment is achieved by testing the spectrum of the output light at the through-end, when the asymmetry of the spectral sidebands is at its maximum. Or π. When When the frequency is close to 0, the calculated single-sideband frequency comb is as follows: Figure 3 As shown in (a), the comb teeth are nearly flat in the 6nm wavelength range, the comb power fluctuates in the range of 2-3.5dBm, and the number of comb teeth is 76. Moreover, the simulation results and theoretical calculation results are consistent. Figure 3 (b) in the above is in good agreement.

[0069] Furthermore, the modulation bandwidth and efficiency can be improved by optimizing the fabrication process of the electro-optic phase modulator and intensity modulator. Increased electro-optic modulation bandwidth and efficiency can further enhance the spectral width of the flat electro-optic frequency comb and reduce power consumption.

[0070] The relevant technical solutions are the same as in Embodiment 1, and will not be repeated here.

[0071] Example 3

[0072] A system for generating a flat electro-optic frequency comb includes: a device for generating a flat electro-optic frequency comb as described above, a single-frequency light source for inputting single-frequency light into the input and output waveguides in the device, a first radio frequency source for applying a first modulation electrical signal to a ring resonant cavity to achieve phase modulation, and a second radio frequency source for applying a second modulation electrical signal to the ring resonant cavity to achieve amplitude modulation.

[0073] The relevant technical solutions are the same as in Embodiment 1, and will not be repeated here.

[0074] In summary, this invention addresses the problems of low comb power and unevenness of existing electro-optic frequency combs by proposing a flat electro-optic frequency comb with a simple structure, high comb power, and high comb flatness, which has significant value for practical applications in the fields of precision measurement and optical communication.

[0075] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for generating a flat electro-optic frequency comb, characterized in that, include: An electro-optic phase modulator and an electro-optic amplitude modulator are integrated and cascaded within a ring resonant cavity that transmits optical signals. Radio frequency modulation signals are applied to the electro-optic phase modulator and the electro-optic amplitude modulator, respectively, to obtain a flat electro-optic frequency comb within the micro-ring resonant cavity. The ring resonant cavity is constructed of an electro-optic medium doped with gain material or of an optical fiber loop with optical gain elements, such that the optical signal generates an optical gain of 3dB per revolution within the ring resonant cavity. The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined by the following method: By utilizing an electro-optic phase modulator and an electro-optic amplitude modulator cascaded within a ring resonant cavity, along with optical gain, non-reciprocal coupling between photonic frequency modes is constructed. This allows for the determination of the relationship between the coupling coefficient between frequency modes and the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulation electrical signals. Based on this relationship, and the relationship between the power ratio of adjacent frequency modes and the coupling coefficient between frequency modes when the input light satisfies the ring resonant cavity resonance condition, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators are determined when the power ratio of adjacent frequency modes is 1.

2. The generation method as described in claim 1, characterized in that, Electro-optic phase modulation modulated electrical signal Among them, V 01 The amplitude of V1, Let V1 be the initial phase, Ω be the modulation frequency, and t be the continuous time.

3. The generation method as described in claim 2, characterized in that, Electro-optic amplitude modulation modulation signal Among them, V DC For DC bias, V 02 The amplitude of V2, Let Ω be the initial phase of V2, Ω be the modulation frequency, and t be the continuous time.

4. The generation method as described in claim 3, characterized in that, The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation signals of the two modulators satisfy the following: β1 << 1, β2 << 1, power ratio of adjacent frequency modes Where γ is the linewidth of the ring resonator, and T R β1 is the time required for one cycle of optical signal transmission, a is the modulation depth of the electro-optic phase modulator, and β1 is the time required for one cycle of optical signal transmission. n and a n-1 Let i represent the amplitude of the nth-order frequency mode and the amplitude of the (n-1)th-order frequency mode, respectively, where i represents the imaginary unit and β represents the amplitude of the (n-1)th-order frequency mode. a The modulation depth of the electro-optic amplitude modulator, β2 = β a / 2, This represents the phase difference between the two modulated electrical signals.

5. The generation method as described in claim 4, characterized in that, 6. A device for generating a flat electro-optic frequency comb, characterized in that, include: Input and output waveguides and a ring resonant cavity; the input and output waveguides are used for the input and output of optical signals, and the ring resonant cavity is composed of an electro-optic dielectric doped with gain material or an optical fiber loop with optical gain elements. It integrates cascaded electro-optic phase modulators and electro-optic amplitude modulators to perform electro-optic phase modulation and electro-optic amplitude modulation on the optical signals coupled from the input and output waveguides, and to generate an optical gain of 3dB for each revolution of the optical signal in the ring resonant cavity. The modulation depth of the electro-optic phase modulator, the modulation depth of the electro-optic amplitude modulator, and the phase difference of the modulation electrical signals of the two modulators are all determined by the following method: By utilizing an electro-optic phase modulator and an electro-optic amplitude modulator cascaded within a ring resonant cavity, along with optical gain, non-reciprocal coupling between photonic frequency modes is constructed. This allows for the determination of the relationship between the coupling coefficient between frequency modes and the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the two modulation electrical signals. Based on this relationship, and the relationship between the power ratio of adjacent frequency modes and the coupling coefficient between frequency modes when the input light satisfies the ring resonant cavity resonance condition, the modulation depth of the phase modulator, the modulation depth of the amplitude modulator, and the phase difference between the modulation electrical signals of the two modulators are determined when the power ratio of adjacent frequency modes is 1.

7. A system for generating a flat electro-optic frequency comb, characterized in that, include: A flat electro-optic frequency comb generating device as described in claim 6, used to input a single-frequency light source of single-frequency light into the input and output waveguides in the generating device, and to apply a first modulation electrical signal to a phase modulator integrated in a ring resonant cavity to achieve phase modulation of a first radio frequency source. And a second radio frequency source that applies a second modulation electrical signal to an amplitude modulator integrated within a ring resonant cavity to achieve amplitude modulation.

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