为了在理论和实际中研制能够产生高效平坦宽带中红外超连续谱的光纤, 文章提出一种以三硒化二砷(As2Se3)为背景材料的微结构光纤,利用非线性薛定谔方程计算模拟了光纤的结构参数对色散、耗损与非线性特性的影响, 选取优化结构参数实现高非线性色散平坦全正常色散。采用该结构光纤对中超短脉冲的展宽机制进行分析, 研究了光纤长度、泵浦中心波长、峰值功率以及泵浦宽度等参数对超连续谱生成的影响, 并通过此光纤实现平坦中红外超连续谱的输出。搭建了实验平台, 选取优化的光纤长度和泵浦参数检测了飞秒激光脉冲在As2Se3微结构光纤中的传输过程和输出谱, 实验结果表明, 采用该结构光纤能够生成波长展宽为3~6 μm的高效平坦宽带中红外超连续谱, 此连续谱可应用在物质探测、生物化学、食品检测和环境分析等领域。

In order to fabricate high-efficient flat broadband mid-infrared supercontinuum fiber, a microstructured fiber based on As2Se3 as background material is proposed. By using nonlinear Schrodinger equation, the effects of fiber structure parameters on dispersion, loss and nonlinear characteristics are simulated, and the optimized structure is designed. The optimal structural parameters are selected to achieve high nonlinearity with flattened full normal dispersion. The mechanism of ultrashort pulse broadening is analyzed by using this structure optical fiber. The effects of fiber length, pump center wavelength, peak power and pump width on the generation of supercontinuum are studied, and the output of the flat mid-infrared supercontinuum is realized by this fiber. By building experimental platform, the transmission and output spectrum of femtosecond laser pulses in As2Se3 microstructured fibers are measured by selecting the optimized fiber length and pump parameters. The experimental results show that high efficiency flat broadband mid-infrared supercontinuum with wavelength broadening of 3~6 μm can be generated. This continuous spectrum can be used in the fields of material detection, biochemistry, food detection and environmental analysis.