基于非线性孔硅波导的超快全光调制特性研究

Properties of nonlinear ultrafast all optical modulation for optical signal will be further studied in this project. Firstly, we will theoretically construct the relation between waveguide scale, porosity, pore size and all kinds of linear and nonlinear optical processes including dispersion, self-phase modulation, cross-phase modulation, two photon absorption, free carrier absorption, free carrier dispersion, Raman scattering and four wave mixing, and so on, and then, discuss the influences of the various optical processes on the ultrafast signal with picosecond and femtosecond time duration. Whereafter, various optical devices such as single waveguide, cascaded waveguides, and Mach-Zehnder interferometer, etc. will be designed and simulated to achieve ultrafast all optical modulation technology. The influences of various system parameters and optical processes on the key performance parameters such as extinction ratio, Q factor and bite error ratio, and so on, of modulation signal, will be thoroughly analyzed. Based on the theoretical analyse, the presented design model will experimentally verified. . for modulation signal will be further analyzed so that we can arrive at the goal of optimizing the modulation signal by adjusting the system parameters. Based on the theoretical results, the presented models will be experimentally verified. Therefore, Through the study of this project, The applications of nonlinear porous silicon waveguide in the integrated photonic technology will be further promoted.

本项目将对光信号在孔硅波导中的非线性超快全光调制特性进行深入探究。首先从理论上构建色散、自相位调制、交叉相位调制、双光子吸收、自由载流子吸收、自由载流子色散、拉曼散射和四波混频等线性和非线性光学过程与波导尺度、孔隙率和孔径大小的关系，并讨论各种光学过程对皮秒和飞秒时间持续的超快信号光学特征的影响。然后从理论上探索设计和模拟基于孔硅介质的单波导、级联波导以及马赫-曾德尔干涉结构等光学装置来实现具有不同时间持续的超快全光调制技术，并深入分析不同的系统参数和各种光学过程对调制信号的消光比、Q 因子和误码率等关键性能参数的影响，根据模拟结果，调节系统参数来达到优化调制信号的目的。在理论分析的基础上，对所表达的设计模型进行实验验证。通过本项目的研究，将进一步促进非线性孔硅波导在集成光子技术中的应用。

本项目主要研究了基于非线性孔硅波导的全光调制技术。设计了基于非线性孔硅波导的马赫-曾德尔装置，构建了理论模型，采用泵浦-探测结构获得了在探测光波长处调制深度可达15dB的调制信号。调制信号的时域波形与波导长度、泵浦光强度和时间持续密切相关。通过优化系统参数实现了操作速率达Gb/s的调制技术，实现的调制信号具有高的Q因子和低误码率，其中消光比在10.63dB-13.51dB和眼开比在0.76-0.99之间变化。利用孔硅波导中的非线性调制过程和马赫-曾德尔结构的光传输特性，实现了超快脉冲的产生和压缩，通过调节从两臂输出脉冲的时延，可实现单脉冲和双脉冲输出的灵活切换。详细讨论了孔硅波导中双光子吸收、自由载流子吸收、自由载流子色散、交叉相位调制和自相位调制等各种非线性过程对信号脉冲在时域和频域波形上的联合作用，由于非线性吸收效应导致了输出脉冲被压缩，各种非线性过程的联合作用导致脉冲光谱成剧烈的振荡结构。在新型单模半导体激光器中采用泵浦-探测结构实现了光调制深度高达25dB的全光调制技术，由于激光器中双稳磁滞曲线的影响，通过调节泵浦光的消光比和泵浦光与所选择激光边模的波长失谐来实现不同调制深度的调制信号，通过合理选择波长失谐，实现了7.74dB开光常数比的泵浦光来获得26.63dB调制深度的调制信号，通过扩大泵浦光开光常数比，可获得泵浦光功率动态范围变化大的全光调制技术。利用硅基平台设计了等离子体波导的全光调制技术，通过设计可实现波导分别对TE模和TM的调制，根据调制原理实现了TE偏振控制器，在该控制器中，TM模被截止不能通过波导，相反，TE模实现高消光比通过，从波导输出信号的消光比可达到25dB，调制范围300nm，并且获得的TE模随波导尺度的变化不敏感。通过本项目的研究，将促进光调制技术的应用。