CN-119225052-B - Optimized comb tooth space optical frequency comb generation method and device based on synthetic Moire lattice

CN119225052BCN 119225052 BCN119225052 BCN 119225052BCN-119225052-B

Abstract

A method for generating optical frequency comb with optimized comb tooth space based on synthetic Moire lattice includes such steps as coupling two optical fiber resonant rings with unequal sizes, applying resonant electro-optic phase modulation, and constructing Moire lattice in frequency dimension to output optical frequency comb with comb tooth space being the greatest common divisor of free spectral range of two resonant rings. The invention has simple structure, can realize the generation of a denser optical frequency comb by utilizing a smaller system structure under the condition of not changing the size of the resonant ring, and realizes the controllable electro-optic optical frequency comb output by flexibly adjusting the coupling strength between the two annular resonant rings.

Inventors

YUAN LUQI
LI GUANGZHEN
HE YANYAN
WANG LIJIA
ZHENG YUANLIN
CHEN XIANFENG

Assignees

上海交通大学

Dates

Publication Date: 20260505
Application Date: 20241121

Claims (7)

1. A method for generating an optimized comb tooth space optical frequency comb based on a synthetic Moire lattice is characterized in that the Moire lattice is constructed on a frequency dimension by coupling two optical fiber resonant rings with unequal sizes and applying resonant electro-optic phase modulation so as to output an optical frequency comb with the comb tooth space being the greatest common divisor of the free spectral ranges of the two resonant rings, and further, the spectral distribution of the output optical frequency comb is controlled by changing the coupling strength; The frequency dimension is that a microwave signal is generated through a signal generator and modulated to a free spectrum range matched with an optical fiber resonant ring through an electro-optic phase, and an artificial synthesized frequency dimension is constructed by analogy to the coupling of lattice points in lattices in a real space, each resonant mode is a lattice point of a synthesized lattice, and a synthesized lattice period is a free spectrum range, so that the electro-optic optical frequency comb output with smaller comb tooth space is realized.
2. The method for generating optical frequency combs with optimized comb tooth space based on synthetic Moire lattices according to claim 1, wherein said lattice periods are respectively And Wherein: For the group velocity of light transmitted in the ring, The greatest common divisor of the free spectral range of the two fiber-optic resonant rings, And Respectively two optical fiber resonant rings, and when the two optical fiber resonant rings are coupled, the lattice period can be constructed as Is used for synthesizing the Moire lattices of the lens, Analogous to the twist angle of the moire lattice.
3. The method for generating the optimized comb tooth space optical frequency comb based on the synthetic moire pattern according to claim 1, wherein the spectral distribution is adjusted by scanning the wavelength of the pump source, adjusting the coupling ratio of the two fiber resonance rings, measuring the energy band of the synthetic moire pattern under different coupling ratios or adjusting the wavelength of the pump source to a single wavelength, and measuring the spectral distribution under different coupling ratios.
4. A method of generating optimized comb teeth pitch optical frequency combs based on synthetic moire patterns according to any one of claims 1-3, wherein in an artificially synthesized moire pattern, due to the different free spectral ranges of the two ring resonator rings, sum and difference frequency effects occur between frequency modes, with a center frequency of The pumping light of the first optical fiber is incident into the first optical fiber resonant ring and is subjected to electro-optic phase modulation to generate a frequency interval of When the first group of photoelectric optical frequency combs are coupled into the second optical fiber resonant ring and further subjected to photoelectric phase modulation, the frequency spacing is generated A second group of electro-optic optical frequency combs, wherein And (3) with Is an integer. The first group and the second group of electro-optic frequency combs are cascaded together to form a frequency interval of Is output by the electro-optic optical frequency comb.
5. An optimized comb tooth space optical frequency comb generating device for realizing the method of any one of claims 1-4 is characterized by comprising a pumping source, a double resonant cavity coupling unit and a spectrum detection unit which are sequentially connected, wherein the pumping source is connected with the double resonant cavity coupling unit through an optical fiber coupler, and two resonant rings are connected through an adjustable optical fiber coupler.
6. The device for generating optical frequency combs with optimized comb tooth space according to claim 5, wherein the resonant rings comprise semiconductor optical amplifiers, polarization controllers, electro-optic phase modulators and dense wavelength division multiplexers, wherein the polarization controllers respectively adjust polarization of optical signals in the respective resonant rings and slow axes of the two electro-optic phase modulators are consistent, the two semiconductor optical amplifiers respectively amplify the signal light in the respective resonant rings and compensate loss of the light in the rings so that gain in each ring is approximately equal to loss, the two dense wavelength division multiplexers respectively filter amplified noise generated in the respective resonant rings so as to improve signal-to-noise ratio, the two electro-optic phase modulators respectively perform electro-optic phase modulation on the optical signals in the respective resonant rings so as to generate the electro-optic optical frequency combs, and the adjustable optical fiber coupler adjusts coupling strength of the respective resonant rings.
7. The device for generating an optimized comb tooth space optical frequency comb according to claim 6, wherein the optical fiber coupler, the first semiconductor optical amplifier, the first polarization controller, the adjustable optical fiber coupler, the first electro-optic phase modulator and the first dense wavelength division multiplexer in the first optical fiber resonant ring are sequentially connected, and the adjustable optical fiber coupler, the second polarization controller, the second dense wavelength division multiplexer, the second semiconductor optical amplifier and the second electro-optic phase modulator in the second optical fiber resonant ring are sequentially connected.

Description

Optimized comb tooth space optical frequency comb generation method and device based on synthetic Moire lattice Technical Field The invention relates to a technology in the field of optical information processing, in particular to a method and a device for generating an optical frequency comb with optimized comb tooth space based on a synthetic Moire lattice. Background The concept of optical frequency combs, i.e. optical frequency combs, originates from mode-locked lasers and appears in the frequency domain as a series of equally spaced frequency-distributed comb teeth. The optical frequency comb can be divided into a Kerr optical frequency comb, an electro-optical frequency comb and the like according to a generation mechanism, wherein the electro-optical frequency comb is used for generating sidebands by modulating laser by an electro-optical modulator, so that comb teeth with equidistant frequency are generated. In recent years, the development of an electro-optical frequency comb is greatly promoted by the progress of an integrated chip, and the bandwidth, the stability, the signal-to-noise ratio and the like of the electro-optical frequency comb are greatly improved based on the electro-optical frequency comb generated by a micro-ring resonant ring with a high quality factor. The principle is that electrodes are prepared and microwave signals are loaded on the micro-ring resonant ring, so that the modulation frequency of the microwave signals is equal to the free spectrum range of the resonant ring, and the frequency of sidebands generated by electro-optic modulation is consistent with the resonant frequency of the resonant ring, thereby forming high-efficiency electro-optic optical frequency comb output. The comb tooth spacing of the electro-optic optical frequency comb is determined by the size of the resonant ring, and when the electro-optic optical frequency comb with smaller comb tooth spacing is required to be produced, the size of the resonant ring needs to be increased, which is contradictory to the miniaturization requirement of the integrated chip device. Disclosure of Invention Aiming at the problems that the number of the comb teeth of the optical frequency comb is small, the shape of the comb teeth is easy to generate distortion and the signal noise is low in the prior art, the invention provides the optical frequency comb generating method and device based on the optimized comb tooth space of the synthetic Moire lattice, which have simple structure, can realize the generation of a denser optical frequency comb by utilizing a smaller system structure under the condition of not changing the size of a resonant ring, and realize the controllable electro-optic optical frequency comb output by flexibly adjusting the coupling strength between two annular resonant rings. The invention is realized by the following technical scheme: The invention relates to a method for generating an optical frequency comb with optimized comb tooth space based on synthetic Moire lattice, which comprises the steps of coupling two optical fiber resonant rings with unequal sizes and applying resonant electro-optic phase modulation, the moire lattice is constructed in the frequency dimension to output an optical frequency comb with comb tooth space being the greatest common divisor of the free spectral range of the two resonant rings, and the spectral distribution of the output optical frequency comb is controlled by changing the coupling strength. The frequency dimension is that a microwave signal is generated through a signal generator and modulated to a free spectrum range matched with an optical fiber resonant ring through an electro-optic phase, and an artificial synthesized frequency dimension is constructed by analogy to the coupling of lattice points in lattices in a real space, each resonant mode is a lattice point of a synthesized lattice, and a synthesized lattice period is a free spectrum range, so that the electro-optic optical frequency comb output with smaller comb tooth space is realized. The lattice periods are omega 1＝2πvg/L1＝N1 Ω and omega 2＝2πvg/L2＝N2 Ω respectively, wherein v g is the group velocity of light transmitted in the ring, Ω is the greatest common divisor of the free spectral ranges of the two fiber resonance rings, L 1 and L 2 are the circumferences of the two fiber resonance rings respectively, when the two fiber resonance rings are coupled, a synthetic Moire lattice with the lattice period of N 1N2 Ω can be constructed, and Ω 1:Ω2 is analogous to the torsion angle of the Moire lattice. The spectrum distribution is regulated by scanning the wavelength of the pump source, regulating the coupling ratio of the two optical fiber resonant rings, measuring to obtain the energy band of the synthetic Moire lattice under different coupling ratios or regulating the wavelength of the pump source to be a single wavelength, and measuring to obtain the spectrum distribution under different coupling