飞秒激光直写硫系光波导调控色散产生中红外超连续谱

Mid-infrared (MIR) supercontinuum generation (SCG) in chalcogenide (ChG) waveguide shows great potential for applications in the fields of integrated optics, small display, molecular sensing and all-optic communications. Due to the limitations from material dispersion and the fabrication methods, however, the effective mode area of ChG waveguide is restricted to a large level and very few types are reported. Since the zero dispersion wavelength (ZDW) of ChG waveguide is located in MIR region, only ultra-short MIR laser pulses generated from expensive and complicated optical parametric amplification systems with low average power was used as pumping source for SCG, which blocks its way to applications in more integrated and small-sized devices. In this project we propose As-S and Ge-Sb-S ChG waveguide direct writing with a femtosecond laser. The waveguide dispersion can be accurately engineered either by downsizing the mode area or writing specific cladding structures with the help of femtosecond laser, pushing ZDW to shorter wavelengths to match the well-developed ultra-short fiber laser systems as pumping sources. In this project the mechanism of the laser induced refractive index change, the influence of ChG composition on the refractive index will be investigated. MIR SCG is highly expected in the pre-designed laser written ChG waveguide. The project will play a positive role in developing bright, small-sized and integrated novel MIR supercontinuum light source.

利用硫系光波导的高非线性产生中红外超连续谱在集成光子学、小型光显示、分子探测和全光通信等领域有着潜在重要应用价值，然而受到材料色散和制备工艺限制，硫系光波导模场面积较大且周围结构单一，导致零色散波长限制在中红外区，现普遍采用昂贵复杂的光学参量放大系统产生的低功率中红外超短脉冲激光进行泵浦，这严重限制了光波导易集成化、小型化的特点。本项目提出采用飞秒激光直写As-S和Ge-Sb-S硫系光波导，通过减小模场面积或直写微结构包层的方法对光波导色散进行调控，使得零色散波长向短波方向移动以匹配更加成熟的超短脉冲光纤激光泵浦源。项目拟研究飞秒激光诱导硫系玻璃发生光折变机理、揭示硫系玻璃组成对光折变的影响规律，实现新型硫系光波导的设计与直写，并最终获得中红外超连续谱输出。项目的开展对开发高亮度、小型化、集成化的新型中红外超连续光源将起到积极的推动作用。

利用硫系光波导的高非线性产生中红外超连续谱在集成光子学、小型光显示、分子探测和全光通信等领域有着潜在重要应用价值，然而受到材料色散和制备工艺限制，硫系光波导模场面积较大且周围结构单一，导致零色散波长限制在中红外区，现普遍采用昂贵复杂的光学参量放大系统产生的低功率中红外超短脉冲激光进行泵浦，这严重限制了光波导易集成化、小型化的特点。本项目采用飞秒激光直写As-S和Ge-Sb-S硫系光波导，通过减小模场面积或直写微结构包层的方法对光波导色散进行调控，使得零色散波长向短波方向移动以匹配更加成熟的超短脉冲光纤激光泵浦源，或者通过堆垛法制备光纤预制棒，并拉制出非线性光纤，将超短脉冲激光耦合入光纤产生超连续光谱。项目研究了飞秒激光诱导硫系玻璃发生光折变机理、揭示硫系玻璃组成对光折变的影响规律，并成功制备非线性光波导，通过超短脉冲激光泵浦，最终获得超连续谱输出。项目的开展对开发高亮度、小型化、集成化的新型超连续光源将起到积极的推动作用。