磷化铟纳米线-硅光子晶体纳腔的模场耦合及电光调制器

The high performance of silicon-based passive photonic devices and their compatibility with CMOS fabrication process make them have great potentials in photonic integrated chips. However, the existing silicon-based electro-optic modulators are mainly based on thermal-optic effect and plasma dispersion effect, which are suffered from slow speed, large insertion loss, and complicated fabrication processes, etc. Also, silicon is a centrosymmetric crystal, which hinders its construction of a modulator with the linear Pockels electro-optic effect. This project proposes to integrate an indium phosphide nanowire onto a photonic crystal nanocavity to demonstrate a high-performance electro-optic modulation on account of the strong linear electro-optic effect in indium phosphide nanowire and the mode coupling between nanowire and nanocavity. To achieve these, following major studies will be carried out: (1) Investigating characteristics and physical mechanisms in the mode coupling between nanowire and nanocavity; (2) Constructing the integrated electro-optic modulators and characterizing their performances. Two key scientific problems are required to be solved: (1) How to design the nanowire-nanocavity structure to maximize the mode coupling between nanowire and nanocavity; (2) How to build the external electrical fields for the electro-optic modulator. The novelties of this proposal include: (1) Realizing effective light-nanowire interactions by accurately integrating the nanowire on the photonic crystal nanocavity via their strong mode coupling; (2) Constructing electro-optic modulators on the photonic crystal nanocavity with the assistance of the strong linear electro-optic effect in the indium phosphide nanowire. The results obtained from above studies are expected to not only provide a new routing for realizing silicon-based active photonic devices, but also present possibilities to develop nanowire-based optoelectronic devices.

硅基被动光子器件的高性能及其与CMOS制备工艺的兼容性，使其在光子芯片方面潜力巨大。然而，现有硅基电光调制器主要基于热光和等离子体色散效应，存在速率低、插损大或工艺繁琐等问题。而硅作为中心对称晶体，难以构建基于线性Pockels电光效应的调制器。本项目拟在硅光子晶体纳腔上集成具有强线性电光效应的磷化铟纳米线，研究二者模场耦合并辅助实现电光调制。主要研究：①纳米线与硅光子晶体纳腔间模场耦合特性及物理机制；②二者集成电光调制器的构筑及性能表征。拟解决关键问题是：①支持纳米线-硅光子晶体纳腔高效模场耦合的复合结构设计；②拟集成电光调制器上外加电场的构建。创新点有：①在硅光子晶体纳腔上精确集成纳米线，通过两者强烈的模场耦合，实现纳米线与光场的有效作用；②借助磷化铟纳米线的强线性电光效应，构建硅基集成电光调制器。研究成果有望为实现硅基主动光子器件提供新途径，也为开发纳米线的光电子器件应用提供新思路。

硅基无源光子器件的高性能及其与CMOS制备工艺的兼容性，使其在光子芯片方面潜力巨大。然而，现有硅基电光调制器主要基于热光和等离子体色散效应，存在速率低、插损大或工艺繁琐等问题。而硅作为中心对称晶体，难以构建基于线性Pockels电光效应的调制器。本项目拟在硅光子晶体纳腔上集成具有强线性电光效应的磷化铟纳米线，研究二者模场耦合并辅助实现电光调制。项目从新型光子结构设计、III-V族纳米线二阶非线性特性与光学模式特性揭示、纳米线-光子晶体纳腔复合结构实现高效二阶非线性过程以及基于谐振腔增强光与物质相互作用的高效片上器件设计等方面均取得了成果，达到了预期的研究目标。. 取得结果有：（1）为了提升纳米线与光学纳腔的模式耦合，设计了几种新型谐振腔，包括：品质因子高达105的光子晶体纳腔、基于两种不同的光子晶体纳腔交替耦合的Su-Schrieffer-Heeger （SSH）拓扑结构、一维拓扑光子晶体纳腔结构，磁响应的金“开口环”-光子晶体纳腔；（2）为了计算纳米线中的电光系数，基于对纳米线激光器中的自频率转换现象的建模，实验上研究了纳米线中的二阶非线性效应，得到了纳米线中二阶非线性系数矩阵与纳米线生长方向之间的关系；此外，为了实现纳米线-光子晶体纳腔电光调制器片上集成，研究了纳米线与光子晶体之间的模式耦合特性, 并提出了一种片上集成纳米线激光器的策略；（3）进一步，将磷化铟纳米线集成于光子晶体波导上，在光子晶体波导上实现了纳米线诱导产生的谐振腔，在毫瓦级连续激光泵浦下，实现了磷化铟纳米线上的光波频率上转换过程，包括二次谐波与和频过程；（4）在以上基础上，基于二维晶体硒化镓与片上氮化硅微环的集成结构，实现了最高 849%/W（123%/W）的二次谐波（和频）转换效率；此外，将硫化钼热电子探测器集成于片上氮化硅微环上，实现了可用于通讯波段的片上光电探测器。. 研究成果有望为实现硅基有源光子器件提供新途径，也为开发纳米线的光电子器件应用提供新思路。