3-5μm中红外激光在光通信、环境监测、医疗、工业加工、光电对抗等领域具有重要应用。本项目针对~3.5μm中红外超短脉冲的应用需求及传统锁模技术难以适用于中红外波段的局限，提出将具有更加优良光学特性的层状黑磷材料作为可饱和吸收体应用到3.5μm波段Er:ZBLAN光纤激光器中，开展基于黑磷调制的3.5μm波段被动锁模脉冲产生机理及其特性调控研究。理论和实验探索3.5μm波段Er:ZBLAN光纤激光器双波长强泵浦方案下增益光纤主要光谱参数变化（如上能级寿命、能量上转换和再吸收系数等）和谐振腔参数等对激光性能的影响，揭示3.5μm波段激光高效高功率运转规律及内在机理；阐明黑磷可饱和吸收体各宏观参量（饱和吸收强度、调制深度、非饱和损耗等）及谐振腔参数与锁模脉冲时域、频域性质的内在关系，研制中红外黑磷锁模器件并优化谐振腔参数，实现稳定的3.5μm波段大能量超短脉冲激光输出。

Mid-infrared laser emissions in 3-5μm have greatly important applications in areas such as telecommunications, atmosphere monitoring, biomedicine, industrial processing and national defence. In this application, a promising ultra-short pulsed lasing scheme at ~3.5μm is proposed in the Er:ZBLAN fiber laser considering the great demand of ultra-short pulsed lasers at this special wavelength but suffering from lacking efficient mid-infrared passive mode-locking components at present. We are applying a new 2D material of black phosphorus (BP) with superb nonlinear optical properties as the mode-locker in ~3.5μm Er:ZBLAN fiber laser and investigate the properties control and efficient generation mechanism of ultra-short pulses at ~3.5μm based on BP. Impact of major spectroscopic parameters of Er:ZBLAN fiber including the energy lifetime, up-conversion and reabsorption coefficient, etc. and cavity conditions on the ~3.5μm lasing performance will be theoretically and experimentally investigated under the dual-wavelength intense pumping scheme in order to recovery the intrinsic mechanism for highly efficient operation. The relationship between the broadband nonlinear optical properties of BP involving typical parameters such as saturable intensity, modulation depth, nonsaturable loss etc. and both the temporal and spectral characteristics of mode-locking pulses are to be studied. Based on qualified BP saturable absorber with appropriate parameters, potential to obtain a stable, ulstra-short pulses at ~3.5μm will be explored experimentally.