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中红外波段包含极其重要的大气窗口和众多分子的指纹区,基于硫系玻璃的中红外光纤激光器逐渐引起人们的重视。由于硫系玻璃具有极高的非线性和色散特性,脉冲激光在硫系光纤中的展宽成为发展中红外超短激光必须解决的重要问题。针对脉冲激光在硫系光纤中传输的展宽问题,设计线性啁啾光纤光栅,用于补偿高斯脉冲激光经过光纤之后的色散展宽。模拟结果表明:光纤色散导致的脉冲展宽可以通过线性啁啾光纤光栅进行很好的补偿。进一步研究发现,通过对设计的啁啾光纤光栅运用高斯变迹函数进行切趾优化,可以显著改善色散补偿的效果,以获得对脉冲激光色散展宽的完全补偿。文中的研究对于设计高质量的硫系中红外光纤激光器具有理论指导意义。
The mid-infrared band contains extremely important atmospheric windows and fingerprinting regions of many molecules. Mid-infrared fiber lasers based on chalcogenide glass have drawn increasing attention. Due to the extremely high nonlinearity and dispersion characteristics of chalcogenide glass, broadening of pulsed lasers in sulfur-based fibers has become an important issue that must be addressed in developing mid-infrared ultra-short lasers. In order to broaden the transmission of pulsed laser in sulfur-based optical fiber, a linear chirped fiber grating is designed to compensate the dispersion broadening of the Gaussian pulsed laser after passing through the optical fiber. Simulation results show that the pulse broadening caused by fiber dispersion can be well compensated by linear chirped fiber gratings. Further studies have found that by using Gaussian apodization function to optimize the chirped fiber gratings, the effect of dispersion compensation can be significantly improved to obtain the complete compensation for the dispersion broadening of the pulsed laser. The research in this paper is of theoretical significance for the design of high-quality sulfur-based mid-infrared fiber lasers.