用于产生超连续谱的硫系光子晶体光纤的色散特性

Dispersion properties of chalcogenide glass photonic crystal fiber for mid-IR supercontinuum spectrum generation

光子晶体光纤具备的无截止单模、模场面积可调和色散可控的特性，使其在超连续谱的产生中具有独特的优势。超连续谱的产生条件之一，是所使用的光纤须具有高的非线性，而硫系玻璃非线性系数极高，因此利用硫系玻璃光子晶体光纤产生超连续谱的研究备受关注。采用熔融-淬冷法制备Ge23Sb12S65硫系玻璃，并以此为基质设计了用于超连续谱产生的高非线性光子晶体光纤。采用多极法分析光纤孔间距Λ、孔径比d/Λ等对光纤的色散零点位移、色散平坦调控、损耗及模场面积的影响，最终得到当Λ=2μm，d/Λ=0.43时，可获得2~4μm平坦色散的高非线性光子晶体光纤结构。

Photonic crystal fibers own the properties of endless single-mode, adjustable mode area and controlled dispersion which make it particularly suitable to achieve supercontinuum spectrum generation. One necessary condition of supercontinuum spectrum generation is that the used media has high nonlinear coefficient. Chalcogenide glass pocesses the property of very high nonlinear, so using chalcogenide glass photonic crystal fiber to generate supercontinuum spectrum has attracted widespread attention. In this work, Ge23Sb12S65 chalcogenide glass was fabricated using melt-quenching method and measured to have high nonlinear refractive index. Chalcogenide glass photonic crystal fibers used for mid -IR supercontinuum spectrum generation was designed and studied with multi-polar method. By controlling the hole spacing Λand the aperture ratio d/Λ, the dispersion, loss and mode area optimized. Finally, a flattened dispersion photonic crystal fiber in the range 2-4μm was obtained, withΛ=2μm and d/Λ=0.43.