• 微波光子技术 •

### 基于双环结构的谐波锁模光电振荡器仿真模型

1. 电子科技大学光电科学与工程学院电子薄膜与集成器件国家重点实验室，四川 成都 611731
• 收稿日期:2021-08-01 修回日期:2022-01-27 出版日期:2022-04-25
• 通讯作者:
• 张旨遥
• 作者简介:
• 吴懿霖 男，2000年出生，四川德阳人.电子科技大学光电科学与工程学院本科生.主要研究方向为微波光子学.E-mail: wuyilin@std.uestc.edu.cn
曾 珍 女，1994年出生，四川广元人.电子科技大学光电科学与工程学院博士研究生.主要研究方向为微波光子滤波器和光电振荡器.E-mail: zengzhen94@std.uestc.edu.cn
章令杰 男，1993年出生，浙江嵊州人.电子科技大学光电科学与工程学院博士研究生.主要研究方向为微波光子学.E-mail: zhanglingjie1993@std.uestc.edu.cn
张旨遥（通讯作者） 男，1983年出生，四川井研人.电子科技大学光电科学与工程学院教授.主要研究方向为光电子技术. E-mail: zhangzhiyao@uestc.edu.cn
刘 永 男，1970年出生，四川富顺人.电子科技大学光电科学与工程学院教授，博士生导师.主要研究方向为光电子技术和微波光子技术.E-mail: YongLiu@uestc.edu.cn
• 基金资助:
• 科技部国家重点研发计划 (2019YFB2203800); 国家自然科学基金重大科研仪器研制项目 (61927821); 中央高校基本科研业务费面向重大需求类项目 (ZYGX2020ZB012)

### Simulation Model for Harmonically Mode-Locked Optoelectronic Oscillator Based on A Dual-Loop Architecture

WU Yi-lin, ZENG Zhen, ZHANG Ling-jie, ZHANG Zhi-yao(), Liu Yong

1. State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Engineering, University ofElectronic Science and Technology of China, Chengdu, Sichuan 611731, China
• Corresponding author:
• ZHANG Zhi-yao
• Supported by:
• National Key Research and Development Program of the Ministry of Science and Technology (2019YFB2203800); National Major Scientific Research Instrument Development Project, NSFC (61927821); Fundamental Research Funds for the Central Universities Targeted to Major Project (ZYGX2020ZB012)

Abstract:

A simulation model is proposed for a harmonically mode-locked optoelectronic oscillator(OEO) based on a dual-loop architecture and bias modulation. The model includes bias modulation of the electro-optic modulator for mode locking, convolution of microwave signals and filter impulse response for mode selection, and time-domain interference of signals in two cavities for super-mode noise suppression. Numerical simulation is carried out based on the improved pulse tracking method to realize synchronous pulse evolution in two cavities. Through using this model, the waveform, the electrical spectra, the super-mode noise suppression and the phase noise characteristics of the generated microwave pulse trains under harmonic mode locking are numerically simulated, where the simulation results fit in with the experimental results. The proposed model can be used to design a harmonically mode-locked OEO based on a dual-loop architecture and bias modulation, and study the dynamic process in the dual-loop cavity, which is conducive to achieve microwave signals with super-mode noise suppression ratio.

Extended Abstract

A dual-loop harmonically mode-locked optoelectronic oscillator (OEO) is proposed based on bias modulation. By using this scheme, the supermode noise of the generated microwave pulse signal from the OEO under harmonic mode locking state can be effectively suppressed via the Vernier effect introduced by the dual-loop architecture. In the proposed scheme, harmonic mode locking can be achieved in the OEO cavity when the direct-current (DC) bias port of the electro-optic modulator is driven by a periodical signal with a frequency N (N≥2) times of the free spectral range of the OEO cavity. In such a case, a high-order mode-locked microwave pulse signal can be generated by the OEO. Benefited from the dual-loop architecture, the supermode noise in the harmonic mode locking process can be greatly suppressed. A simulation model of the dual-loop harmonically mode-locked OEO based on bias modulation is established. The kernel of the simulation model includes the following three parts. Firstly, the phase locking between different longitudinal modes in the OEO cavity is realized by the bias modulation of the electro-optic modulator. Secondly, the mode selection in the OEO cavity is calculated through the convolution of the microwave pulse signal and the filter impulse response. Thirdly, the supermode noise suppression is achieved by the time-domain coherent superposition of the signals in the two loops. An improved pulse tracking method is used to simulate the start-up process of the microwave signal in the dual-loop harmonically mode-locked OEO, where synchronous pulse evolution in the two loops is realized. Through numerically solving this proposed model, the waveforms, the spectra, the supermode noise suppression and the phase noise characteristics of the generated microwave pulse trains from the dual-loop OEO under harmonic mode locking are simulated. The simulation results fit in with the experimental results. Hence, the feasibility of using the dual-loop architecture to achieve supermode noise suppression in the harmonically mode-locked OEO is verified. The proposed model can be employed to design a dual-loop harmonically mode-locked OEO with a high supermode noise suppression ratio. In addition, it can also be used to study the dynamic process in a dual-loop optoelectronic resonator.