Ge-Sb-Se硫系玻璃拉曼增益特性研究∗

摘要

本文制备了As2S3, As2Se3, Ge20Sb15Se65和Ge28Sb12Se60(mol%)四种硫系玻璃,测试了样品的折射率、红外透过及拉曼光谱.利用自发拉曼散射理论,并结合测量的拉曼光谱数据,通过将硫系玻璃与石英玻璃样品的拉曼光谱作对比的方法计算了四种硫系玻璃的拉曼增益系数gR.结果表明： As2S3玻璃在340 cm−1拉曼频移处gR为60×10−13 m/W, As2Se3玻璃在230 cm−1拉曼频移处gR为223×10−13 m/W,与文献报道结果基本相符.与传统光纤拉曼增益系数实验测定法相比,此方法为探索新型高拉曼增益的硫系玻璃组成提供了极大的便捷.应用此方法,计算得出Ge20 Sb15 Se65和Ge28 Sb12 Se60玻璃在200 cm−1拉曼频移处的gR值分别为215×10−13 m/W和111×10−13 m/W.以上结果表明,不含有毒As元素的Ge-Sb-Se硫系玻璃其增益系数可达普通石英玻璃的200倍以上,为环境友好型拉曼光纤激光器基质材料提供了一种全新的可能.%Previously reported chalcogenide glass Raman fiber lasers are made of glass compositions such as As2S3 or As2Se3. However, due to the high toxicity of the element arsenic, there is a potential risk in the glass preparation, fiber drawing, and testing processes. Therefore, we need to explore new environmentally friendly chalcogenide glasses that do not contain As for Raman fiber lasers. Studies have shown that the chalcogenide glasses of Ge-Sb-Se system have excellent infrared transmissions and good environmental friendliness, and thus they are excellent candidates for chalcogenide glass Raman fiber lasers. However, their Raman gains have not been reported. Then Raman gain coefficients can be obtained by experimental measurements and theoretical analyses. The experimental method requires expensive laboratory equipments, a complex optical path, and precision adjustments. Therefore, the design and preparation of new chalcogenide glass fiber with high Raman gain require the theoretical analysis of the Raman gain characteristics in a particular glass component glass. In this work, four chalcogenide glasses, respectively, with compositions of As2S3, As2Se3, Ge20Sb15Se65 and Ge28Sb12Se60 (mol%) are prepared. Refractive indices, infrared transmission and Raman spectra of these glass samples are measured. By using spontaneous Raman scattering theory combined with the measured Raman spectral data, the values of Raman gain coefficient gR of the chalcogenide glasses are calculated and calibrated by a quartz glass sample. Results show that the gR of As2S3 glass is 60 × 10−13 m/W at 230 cm−1 Raman shift and the gR of As2Se3 glass is 223 × 10−13 m/W at 340 cm−1 Raman shift, which are consistent with the experimental results reported in the literature. Compared with the traditional method, the present method used for calculating the fiber Raman gain coefficient provides great convenience for exploring new chalcogenide glasses with high Raman gain. By using this method, we obtain the gR values of Ge20Sb15Se65 and Ge28Sb12Se60 glasses at 200 cm−1 Raman shift, which are 215 × 10−13 m/W and 111 × 10−13 m/W respectively. Meanwhile, we analyze the effects of composition and network structure of chalcogenide glass samples on the Raman gain coefficient and gain spectrum. There are two Raman peaks at 165 cm−1 and 200 cm−1 Raman shift, which are attributed to Ge—Ge bond vibration and Ge—Se bond vibration of common apex GeSe4/2 tetrahedral structure respectively. It could be found that the Raman gain coefficient of Ge20Sb15Se65 glass is bigger than that of Ge28Sb12Se60 glass at 200 cm−1 Raman shift because of more Ge—Se bonds. By further optimizing the ratio of components of Ge-Sb-Se chalcogenide glass, we could obtain higher Raman gain coefficient at a particular frequency shift. These results show that the Raman gain coefficient of Ge-Sb-Se chalcogenide glass without poisonous element is up to over 200 times that of the ordinary quartz glass, which provides a new possibility for environment-friendly Raman fiber laser material.