基于同步双波长激光泵浦的石墨烯宽带波长转换中红外飞秒脉冲生成机理与实验研究

2-5 µm mid-infrared (mid-IR) ultrashort pulsed laser sources are of great importance for many applications (including medicine, military etc). An important way to produce femtosecond pulses operating in the mid-IR region is by means of nonlinear parametric processes which include an ultrashort pulsed laser as the pump interacting nonlinearly with a frequency converter. To date, most mid-IR short pulsed laser sources produced through this approach are complex and bulky. This is due to the limitations of the pumps and converters, e.g. difficulties of the synchronization between different individual lasers, lack of wavelength conversion devices with all-fiber architectures. The focus of this proposal is to develop wavelength tunable, high-peak power synchronized fiber lasers through a common graphene saturable absorber and all-fiber integrated graphene-based broad bandwidth wavelength converters for femtosecond mid-IR pulse generation. There are three main research aspects: the establishment of the experimental and numerical studies of wavelength tunable, high peak power dual-wavelength fiber lasers, highlighting mechanisms, dynamics and outlining optimized geometries for peak power scaling; the design and development of highly nonlinear graphene-based all-fiber integrated wavelength converters that comply with a monolithic approach; and the development of a 2.6-3.2 µm wavelength tunable, short pulsed (<500 fs) mid-IR all-fiber source. We anticipate that the research outlined in this proposal will establish a further understanding of mechanism of the nonlinear interaction between light and matter, and will prove to be a disruptive technology and offer a new paradigm for compact, robust and easy-to-use ultrashort pulsed mid-IR sources.

2-5µm中红外超短脉冲激光源具有重要应用价值。利用超短脉冲激光泵浦结合非线性波长转换器件是通过非线性过程实现中红外飞秒脉冲重要途径之一。但现有研究受限于多个泵浦源之间难于同步、泵浦源峰值功率低、波长转换器件无法与光纤集成等问题，因而难以实现小型集成光源。本项目利用石墨烯具有的宽带可饱和吸收和强三阶非线性响应特性，提出通过共用石墨烯的波长可调谐高峰值功率双波长泵浦激光和全光纤石墨烯波长转换器，实现全光纤中红外波长可调谐飞秒脉冲源。拟开展的研究内容主要有：揭示共用石墨烯的双波长脉冲同步机理，实现高峰值功率全光纤双波长同步激光器；设计和研制结合微纳光纤的高非线性石墨烯波长转换器件，探索光纤器件中光波模式与石墨烯非线性作用机理；实现2.6-3.2µm间可调谐、脉冲宽度<500fs的中红外脉冲源。研究成果将有助于在光与物质作用机理等科学问题上获得新认识，也为实现小型飞秒脉冲激光源提供新思路。

2-5 μm中红外超短脉冲激光在医学、军事和科研等方面具有特殊的重要地位。利用非线性光子器件的光学特性结合超短激光脉冲技术是实现中红外飞秒脉冲的重要途经之一。但现有研究受限于非线性光子器件工作带宽窄、环境稳定性差、输出功率低等问题，制约了小型集成化光源的实际应用与发展。.在本项目的研究中，我们开展了基于二维纳米材料高环境稳定性宽带超快光纤激光器的研究：利用喷墨打印技术研制了多种新型二维纳米材料光子器件，显著提高非线性器件的光学均匀性及可靠性，突破了基于二维纳米材料锁模激光器运转性能及稳定性差的瓶颈；通过对过渡金属硫化物带隙边缘态的精准调控，突破了材料本征能级带宽的限制，实现了工作范围可达微米量级的宽带超快光开关器件；通过研制高性能基于二维纳米材料全光纤结构的非线性器件，获得了光谱拓展的新方法，实现了光纤集成的百飞秒近、中红外激光光源；通过研究基于纳米材料的同步及波长转换器件，探索了光纤器件中光波模式与纳米材料非线性作用机理，获得了实现小型飞秒脉冲激光源的新途径。本项目的研究成果不仅促进了在光与物质作用机理等科学问题上获得新认识，且有望作为新的小型集成化光源推进飞秒脉冲激光在环境、传感、军事等应用领域的研究发展。.在项目上述执行期间，在Nature Communications、Advanced Optical Materials等SCI期刊发表论文8篇，国际会议论文11篇，相关工作入选2017年激光领域十大技术进展，并被《Laser Focus World》、《China Daily》等专题报道。受邀撰写综述论文2篇，英文专著章节1章，申请了国家发明专利1项，指导了6位研究生。