基于重构时间-波长序列的快速高分辨光谱分析技术及核心器件研究

Optical spectrum analysis is an essential method to study the interaction between light and matter. To explore some ultrafast dynamics, it is demanded that the optical spectrum analysis should have high acquisition frame rate. This project is mainly focused on the ultrafast spectroscopy, aimed at realizing over 10-MHz frame rate, 1-pm spectral resolution, and 35-nm observation bandwidth. Reconstruct the time-wavelength sequence based on the temporal focusing mechanism, as well as the high-speed temporal detection, and sequentially carry out theoretical analysis, chip development, system implementation and testing. Leverage the temporal magnification of the dual optical frequency combs structure, to overcome the bandwidth limitation of the temporal focusing mechanism, and realize high spectral resolution. Mainly explore some core devices based on the optical integration technology: enlarge the conversion bandwidth of the nonlinear parametric mixing waveguide; improve the repetition rate of the micro-ring cavity, and its phase-locking schemes; for the combination of these two mechanisms, explore the on-chip implementation of the pulse envelop extraction. Explore higher-order dispersion control in the temporal imaging system to achieve finer resolution, and improve the temporal stability to achieve high spectral accuracy. Leverage the proposed scheme to observe some ultrafast spectral dynamics, and combine it with the measurement of some other dimensions to realize the ultrafast temporal acquisition.

光谱分析技术是研究光与物质相互作用的重要手段，而针对一些快速动态过程的研究，对光谱采样频率有着越来越高的要求。本项目主要研究快速高分辨大带宽的光谱分析，目标实现不小于10MHz的采样频率、1pm的光谱分辨率以及35nm的观测带宽。通过时域聚焦实现重构时间-波长序列，结合高速时域探测技术，开展理论分析、芯片研制、系统搭建与测试工作。通过差频双光频梳的时域放大特性，与时域聚焦方案结合，克服时域探测带宽的限制，实现高分辨的光谱分析。重点研究基于光子集成技术的核心器件，探索大转换带宽的非线性波导和非简并四波混频过程；探索高重复频率的微环及锁相方式，提高采样频率；探索两种方案的结合，设计片上的脉冲包络提取。研究高阶色散控制，优化时域聚焦，提升光谱分辨率；研究时域稳定性，提升光谱的绝对精度。最终利用本项目方案，研究和观测一些超快光谱动态过程，探索更多维度测量应用与高速时域探测的结合。

光谱分析技术是研究光与物质相互作用的重要手段，而针对一些快速动态过程的研究，对光谱采样频率有着越来越高的要求。传统光谱分析技术帧率受限于扫描或阵列探测的速率，通过时域聚焦方案重构时间-波长序列，将光谱信息实时转换到时间轴上，可实现快速高分辨光谱分析。本项目围绕时域聚焦光谱分析系统，研究其性能参数提升和超快应用拓展，具体研究成果包括如下内容：第一，时域聚焦系统的理论创新。通过时域聚焦方案实现了对任意发射光谱的超快测量，建立了理论仿真模型，为时域聚焦系统的优化及孤子光频梳的产生机理提供了理论基础。第二，核心集成器件的设计与优化。通过光子集成技术，分别实现了高重频微腔孤子光频梳、大转换带宽参量混频非线性波导、低损耗氮化硅片上大色散模块、及大带宽光电探测芯片。第三，时域聚焦系统的方案创新与性能提升。通过高阶色散补偿及双波段时分复用，在10MHz采集帧率下，将观测带宽提升至58nm；通过双光频梳异步光采样，将光谱分辨率提升至1pm以下；通过大带宽相干探测实现光谱相位的恢复。第四，拓展时域聚焦光谱分析的应用方向。在超快动态过程测量、微纳器件机理表征、超快射频谱分析、超快光谱成像系统等方向开展应用研究，首次实现了频率布洛赫振荡及载流子瞬态光谱等超快过程观测。在本项目资助下，发表期刊论文40篇和会议论文22篇，包括Nature Communications 2篇、Laser & Photonics Reviews 2篇、Advanced Optical Materials 1篇、Communications Physics 1篇、APL Photonics 5篇、Journal of Lightwave Technology 4篇、Optics Letters 8篇、Optics Express 10篇。培养博士生18名，培养硕士生5名，结题成果达到预期目标。