石墨烯可饱和吸收参数调控与激光器锁模应用研究

Since graphene was experimentally demonstrated to exhibit ultra-wideband saturable absorption in 2009, it has been used to mode-lock solid-state and fiber lasers across a wide spectral range spanning 800nm-2500nm. However, compared with Semiconductor Saturable Absorber Mirrors (SESAMs), which feature multiple design freedoms and highly customized nonlinear absorption parameters, both the parameter range and parameter controllability of graphene saturable absorbers have been limited. This project targets to realize enhanced and controllable parameters of graphene saturable absorbers via local field enhancement effect provided by plasmonic metamaterial's surface plasmon resonance. Through characterizing the enhancement features over a wide spectrum covering visible to mid-infrared,we intend to probe the physical mechanisms invovled in the near field enhancement, and correlate the optimized design and fabrication method with the parameter control guidelines for the new plasmonics-graphene saturable absorber devcie. We will proceed to verify the effetiveness of this approach through laser mode-locking experiment, thus constructing a systematic and comprehensive study of this new device proposal. This project, upon successful implementation, will not only expand the available parameter range for the optimization of graphene based pulsed lasers, thus leading to greatly enhanced stability and flexibility of such lasers, it may also help drive graphene saturable absorber's mode-locked operation into unconventional spectral regions such as visible and mid- or far-infrared. The findings of this project will pave the way for graphene saturable absorbers to develp into a more sophisticated device structure featuring multiple parameter control mechanisms.

自2009年石墨烯被证明具有超宽带可饱和吸收特性以来，基于石墨烯的可饱和吸收体已经在800nm-2500nm的多个波段实现了固体和光纤激光器的锁模运转。然而与半导体可饱和吸收镜丰富的设计自由度和高度可控的非线性吸收参数相比，石墨烯可饱和吸收体的参数范围以及参数可控性还比较有限。本项目提出一种利用超材料表面等离激元共振实现石墨烯可饱和吸收参数增强和调控的新器件结构。通过研究该新型等离激元-石墨烯可饱和吸收器件的参数增强物理机制和宽谱特征，来获得器件结构设计、制备工艺与非线性光学参数调控的关联规律。我们还将验证该新型器件在激光器中的锁模特性，从而构建一个完整的参数可控型等离激元-石墨烯可饱和吸收器件的技术方案。本项目可扩大石墨烯脉冲激光器的参数优化范围，有利于将石墨烯锁模应用扩展到更广的光谱范围（如可见光和中远红外），也为石墨烯可饱和吸收体向具有多重参数调控机制的器件结构发展提供了思路和依据。

项目负责人已在该面上基金项目支持的研究领域开展了系统工作，取得了若干有创新性的研究成果。四年来第一作者/通讯作者身份发表论文17篇，包括Nature Communications2篇，Nanoscale 3篇，Nano Research 1篇，2D Materials 1篇，APL2篇等。项目执行期间，发表国际主流会议论文16篇。主要研究成果包括：发展了石墨烯-等离子激元耦合结构的非线性表征技术。发现了类石墨烯材料-三维狄拉克半金属中的独特的载流子调控效应。阐明了石墨烯-碳纳米管耦合结构中的吸收增强和电荷输运特性。利用低维碳材料，实现了多个工作于中红外2微米的高性能脉冲激光器系统，其中两项激光相关成果被国际知名激光技术杂志《LaserFocusWorld》亮点报道。本项目研究结果进一步明晰了石墨烯-等离子激元复合结构的光响应特性，为低维材料和金属微纳结构的光学应用提供了重要的支撑。