2.0~25.0 $ \mu $m 波段低限制损耗光子晶体光纤的设计

针对 $ 2.0 \sim 25.0 \, \mum $ 波段传输的限制损耗问题, 文章采用数值模拟方法研究影响碲基硫系光子晶体光纤 (photonic crystal fiber, PCF) 限制损耗的主要因素。光纤纤芯和包层材料采用 $ Ge_{20}As_{20}Se_{15}Te_{15} $ 玻璃, 通过改变纤芯直径、空气孔直径和空气孔层数等参数进行 $ 2.0 \sim 25.0 \, \mum $ 波段限制损耗的计算, 结果表明, 影响限制损耗的最大因素是纤芯直径, 限制损耗随着纤芯直径和空气孔直径的增大而显著降低, 随着空气孔层数的增加而降低; 优化设计出一种低限制损耗的 PCF, 结果表明, 当纤芯直径和节距为 $ 8.0 \, \mum $、空气孔直径为 $ 7.2 \, \mum $、包层空气孔层数为 4 时, 该 PCF 在 $ 2.0 \sim 25.0 \, \mum $ 波长范围的限制损耗低于 $ 1.4 \times 10^{-6} \, dB/m $, 满足低损耗传输要求。文章研究结果对 $ 2.0 \sim 25.0 \, \mum $ 波段光信号的传输具有一定的意义。

In consideration of the confinement loss of transmission in the 2.0-25.0 $ \mu $m waveband, the main factors affecting the confinement loss of tellurium-based chalcogenide glass photonic crystal fiber (PCF) are investigated by numerical simulation. The core and cladding materials of PCF are $ Ge_{20}As_{20}Se_{15}Te_{45} $ glass. The confinement loss of PCF in 2.0-25.0 $ \mu $m waveband is calculated by changing the core diameter, air hole diameter and number of air hole layer. The results show that the greatest factor affecting the confinement loss is the core diameter, and the confinement loss decreases significantly with the increase of the core diameter, air hole diameter and number of air hole layer. A PCF with low confinement loss is designed by optimizing the parameters. It is shown that when the core diameter and pitch are 8.0 $ \mu $m, the diameter of air hole is 7.2 $ \mu $m, and the number of air hole layer in the cladding layer is 4, the calculated confinement loss is lower than 1.4 $ \times $10 $ ^{-6} $ dB/m in the spectral range of 2.0-25.0 $ \mu $m, which meets the requirements of low loss transmission. The results are of significance for the transmission of optical signals in the spectral range of 2.0-25.0 $ \mu $m.