Ge-Se基硫系玻璃在通信波段的三阶非线性与光谱特性研究

Third-order optical nonlinearity at communication wavelength and spectral characteristics of Ge-Se based chalcogenide glasses

在Ge-Se二元体系中引入相同摩尔比的Ga,Sn,Sb,Te四种元素,使用熔融淬冷法制备了一系列硫系玻璃.利用吸收光谱获得了不同元素引入下硫系玻璃能带结构的变化,并结合拉曼光谱详细研究了产生光学特性变化的微观表征.使用Z扫描方法测试了各个硫系玻璃样品在1550 nm波长下的三阶非线性参数,发现加入Sn的玻璃的三阶非线性折射率n2最大,达到了6.36×10 17m2/W,且其品质因子大于23,表明Sn引入能够增强硫系玻璃在通信波段的三阶非线性,这一研究结果为以后的高性能红外器件的设计及制备提供了一种环保且性能优良的候选材料.

A series of Ge-Se chalcogenide glasses incorporated with same molar percentage of Ga, Sn, Sb and Te are synthesized by melt-quenching method. The variations of optical band gaps doped with different elements are investigated by absorption spectra, and the relationship of optical band gap with glass network structure is studied by Raman spectra The results show that the doping of heavy metallic elements（except Ga） could reduce the optical band gap of the Ge-Se glass due to the decrease of the number of Se-Se chains or ring bonds. Third-order optical nonlinearities of the glasses are studied by femtosecond Z-scan method at a telecom wavelength of 1550 nm. The results show that the performance of third-order optical nonlinearity of the Ge-Se glass could be improved by doping the above-mentioned elements. By comparison, the Sn-doped Ge-Se glass has a maximum nonlinear refraction index（n2） of 6.36×10^-17m^2/W and a figure of merit of over 23. By combining the experimental results from Raman spectra, the enhancement of third-order optical nonlinearity after the introduction of Sn can be ascribed to the formation of Sn（Se1/2）4tetrahedra that enters into the main frame of Ge-Se glass and results in a stable Ge-Sn-Se network. Te doping could also remarkably enhance the n2 value of the Ge-Se glass, however, it could cause large two-photon absorption, leading to a poor value of figure of merit.The research result shows that chalcogenide glass in Ge-Sn-Se ternary system is an ideal candidate material for designing and fabricating infrared devices with high performance and environmental friendness.