基于GaxIn1-xAsySb1-y/GaSb量子阱SESAM锁模的2 - 2.5 μm波段超快激光特性研究

GaSb- based SESAMs with III-V semiconductor compound GaxIn1-xAsySb1-y/GaSb quantum well structure possess properties of sub-picosecond ultrafast relaxation time, small lattice mismatch, excellent optical quality and feasible design of growth parameters. By incorporating lattice-matched AlAsSb/GaSb distributed Bragg reflectors, an exceptionally broad reflectivity band over hundreds of nanometers is enabled, thus GaxIn1-xAsySb1-y/GaSb quantum well SESAMs become the ideal mode-locker for ultrafast lasers working at spectral region of 2 - 2.5 μm. In this project, with GaxIn1-xAsySb1-y/GaSb quantum well SESAMs as the subject, we plan to characterize the spectral property and nonlinear parameters of SESAMs, study the saturable absorption mechanism and influencing factors at 2 - 2.5 μm band, reveal the basic principle and stable operation conditions for mode-locking in ultrafast lasers at 2 - 2.5 μm, and aim to realize continuous-wave mode-locked and wavelength tunable ultrafast lasers at 2 - 2.5 μm based on the Tm:Lu2O3 and Cr2+:ZnSe crystals with broad gain bandwidths. Through the project, ultrafast femtosecond pulses at 2 μm with Watt-level output and 2.5 μm with hundreds of milli-watts output are expected, which could provide regular basis for the realization of all-solid-state 2 - 2.5 μm ultrafast lasers with high efficiency.

基于GaSb衬底的III-V族半导体化合物GaxIn1-xAsySb1-y/GaSb量子阱结构SESAM具有亚皮秒超快弛豫时间，而且晶格失配小、光学质量好、参数易于调节，嵌入AlAsSb/GaSb材料作为布拉格反射层可实现几百nm的高反射带宽，是2 - 2.5 μm波段超快激光的理想锁模元件。本项目以GaxIn1-xAsySb1-y/GaSb量子阱结构SESAM为对象，表征SESAM的光谱特性和非线性参数,研究其2 - 2.5 μm波段的饱和吸收机理及影响因素，揭示其2 - 2.5 μm波段超快激光锁模的基本原理和稳定运转条件，实现2 - 2.5 μm波段宽带增益介质Tm3+:Lu2O3和Cr2+:ZnSe连续波锁模和波长可调谐超快激光运转，旨在获得2μm波段W级和2.5 μm波段百mW量级飞秒激光输出，为全固态高效率2 - 2.5 μm波段超快激光的实现提供规律性依据。

2-2.5 μm中红外人眼安全超快激光处于典型的大气透明窗口，为众所周知的“分子指纹”光谱区域，不仅在环境监测、远程通信、材料加工、医学、计量学、军事等领域具有极其重要的应用，而且是3 ~ 5 μm中红外和8 ~ 12 μm远红外光学参量振荡器的理想泵浦源，特别是近年来又在超连续谱、中红外光学频率梳、加速器、超短X射线产生等方面展现出重要的应用前景。基于GaSb衬底的III-V族半导体化合物InGaAsSb/GaSb量子阱结构SESAM具有亚皮秒超快弛豫时间，而且晶格失配小、光学质量好、参数易于调节，嵌入AlAsSb/GaSb材料作为布拉格反射层可实现几百nm的高反射带宽，是中红外波段超快激光的理想锁模元件。本项目以GaSb-SESAM为研究对象，表征了SESAM的光谱特性和非线性光学参数，系统研究了其稳定锁模机理和饱和恢复时间的影响因素，建立了GaSb-SESAM微观结构生长参数和锁模超快激光特性之间的内在联系，实现了中红外超快固体激光的稳定运转和大功率输出，为新型中红外超快激光器件的研制提供了重要的技术支撑和理论指导，具有重要的科学意义和应用价值。