基于大芯径多模光纤的高功率可调谐锁模激光器研究

Output average powers and pulse energies of the mode-locked fiber lasers based on single-mode fiber are limited by the small fiber core. In this project, we propose the use of Yb-doped large-mode-area double-clad multi-mode fiber, mode controlling and selecting techniques, and spectral filtering techniques for the generation of high power, wavelength continuously tunable, all normal dispersion mode-locked ultrafast pulses. Pulse shape mechanism of dissipative solitons and their dynamic process in the multi-mode fiber will be investigated theoretically. In the experimental researches, we will focus on the key techniques about the suppression of high modes, all-normal-dispersion mode-locking in the large-mode-area fiber and wavelength tuning. By exploiting the combined action of nonlinear polarization evolution and a spectral filter for self-amplitude- modulation, and a grating-slit configuration for spectral filter and wavelength tuning, our goal is to realize stable all-normal-dispersion dissipative soliton mode-locking in multi-mode fiber. Our researches have an important significance to understand the all normal dispersion mode-locking mechanism in the multi-mode fiber, and develop a new practical approach to generate high power, wavelength tunable femtosecond laser.

基于普通单模光纤的锁模激光器由于纤芯直径较小，限制了其输出功率和脉冲能量。本项目创新性地结合大芯径双包层掺镱（Yb）多模光纤、模式控制与选择技术以及光谱滤波技术，支持高功率、波长连续可调谐的全正色散锁模激光输出。我们将针对多模光纤中耗散孤子脉冲的成型机制及其动力学过程进行探索分析，深入研究光纤中高阶模抑制、大芯径光纤全正色散锁模以及波长可调谐等关键技术的实现。拟采用非线性偏振旋转和光谱滤波技术相结合提供有效的自振幅调制支持稳定的锁模，利用光栅-狭缝结构实现光谱滤波与波长调谐，最终实现多模光纤的全正色散耗散孤子锁模。本项目研究对于揭示多模光纤的全正色散锁模的机制与规律具有重要意义，同时开辟了一条利用大芯径光纤获得高功率可调谐飞秒激光的实用化途径。