二维材料异质结的可控制备与超快光纤激光器研究

Passively mode-locked fiber lasers have widely application in the field of nonlinear optics, laser spectroscopy, life science, laser processing and communication. Semiconductor saturable absorber mirror (SESAM) as a key element for mode-locking, has some inherent drawbacks such as expensive price, complex fabrication process as well as relatively long relaxation time and narrow operation bandwidth owning to the limited energy bandgap of semiconductors. This project aims at to reveal the working mechanism of novel saturable absorber (SA) and the corresponding crucial ultrafast laser technique. By utilizing the two-dimensional material heterostructure to overcome the drawbacks of single two-dimensional material as SA, we will explore the intrinsic physical mechanism for the ultrafast charge carrier relaxation in the atomic layer thickness of heterostructure region, and also the change of energy band that caused by different structure design. By grasping the technique of non-destructive transfer and accurate stack of two-dimensional materials, we aim to fabricate the two-dimensional material heterostructure SAM with merits of high damage threshold and large modulation depth, and further testify the ultrafast relaxation process in heterostructure region by the pump-probe system. Lastly employing the SAM, we aim to achieve stable high energy ultrafast pulse generation with pulse energy beyond 100 nJ and pulse width below 100 fs. Our project is one of the hottest research topic that has perspective in application, which would greatly pave the development of ultrafast photonics for two-dimensional materials.

被动锁模光纤激光器在非线性光学、激光光谱学、生命科学以及激光加工和激光通信等方面具有广泛应用。作为锁模的关键元件，半导体可饱和吸收镜存在弛豫时间长、可饱和吸收带宽窄、价格昂贵和制作复杂的缺点。本课题围绕新型可饱和吸收体的工作机理以及其超快激光技术这一科学问题，采用二维材料异质结来克服单独一种二维材料的不足，从理论上揭示二维材料异质结结区内超快载流子弛豫过程的物理机制和不同结构设计对能带结构的改变。掌握化学气相沉积法生长的二维材料薄膜的无损转移和精准堆栈工艺，制备出高损伤阈值、大调制深度的二维材料异质结可饱和吸收镜，进一步利用泵浦-探测系统实验验证异质结区内载流子超快弛豫过程；最终基于二维材料异质结可饱和吸收镜，在光纤激光器的振荡级实现大能量百飞秒的稳定脉冲产生。相关研究既是前沿热点又具有实用前景，将实质性推动二维材料超快光子学的发展。

被动锁模光纤激光器在非线性光学、激光光谱学、生命科学以及激光加工和激光通信等方面具有广泛应用。作为锁模的关键元件，半导体可饱和吸收镜存在弛豫时间长、可饱和吸收带宽窄、价格昂贵和制作复杂的缺点。本课题围绕新型可饱和吸收体的工作机理以及其超快激光技术这一科学问题，采用二维材料异质结来克服单独一种二维材料的不足，从理论上揭示二维材料异质结结区内超快载流子弛豫过程的物理机制和不同结构设计对能带结构的改变。掌握化学气相沉积法生长的二维材料薄膜的无损转移和精准堆栈工艺，制备出高损伤阈值、大调制深度的二维材料异质结可饱和吸收镜，进一步利用泵浦-探测系统实验验证异质结区内载流子超快弛豫过程；最终基于二维材料异质结可饱和吸收镜，在光纤激光器的振荡级实现大能量百飞秒的稳定脉冲产生。.在项目执行期内，我们探索了不同过渡金属硫化物WS2-MoS2间载流子的弛豫过程，建立了理论模型并实验予以实现，加深了对机理方面的研究探索；实验上指标上也予以完成。还搭建了泵浦-探测系统，对载流子恢复时间予以测量，完善了平台的建设；总计在Photonics Research、Optics Letters、IEEE JSTQE、JLT、AOM等期刊发表SCI论文33篇（包含第一与通信作者16篇），在《中国激光》上发表论文2篇，在《强激光与粒子束》发表论文1篇，授权美国发明专利2项，实用新型专利5项（申请日期均在项目执行期间）。