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利用熔融淬冷法制备了Ge_(20)As_(20)Se_(15)Te_(45)硫系玻璃,测试结果表明该玻璃在中红外波段具有良好的红外透过特性和极高的非线性,采用Z-扫描技术测试其中红外三阶非线性系数高达n2=6.72×10-18m2/W@4μm。以此材料为基质,设计了两种工作在中红外波段的硫系玻璃光纤光栅光开关。利用分布时域传递矩阵法(TD-TMM)和非线性耦合方程模拟计算了光栅光开关的反射谱和波长偏移特性。研究结果表明,通过调节输入光强可以灵活调节光纤光栅的中心波长向短波或长波方向移动,进而可以获得光开关。在调制深度为1×10~(-3)的均匀硫系光纤光栅,获得光开关的功率阈值约为1.6 GW/cm~2,当引入相移光栅后,调制深度可以降低为3×10~(-4),并且其光开关的功率阈值也降低到210 MW/cm~2。
The Ge_ (20) As_ (20) Se_ (15) Te_ (45) chalcogenide glass was prepared by melt quenching method. The results show that the glass has good infrared transmission and high nonlinearity in the mid- The Z-scan technique was used to test the infrared third-order nonlinearity coefficient up to n2 = 6.72 × 10-18m2 / W@4μm. Based on this material, two sulfur-based glass fiber grating optical switches operating in the mid-infrared band were designed. The reflection spectra and wavelength shift characteristics of the grating optical switch were simulated by using distributed time domain transfer matrix (TD-TMM) and nonlinear coupling equations. The results show that by adjusting the input light intensity, the center wavelength of FBG can be flexibly adjusted to move in the shortwave or longwave direction, and then the optical switch can be obtained. The power threshold of the optical switch is about 1.6 GW / cm ~ 2 at uniform modulation depth of 1 × 10 ~ (-3). When the phase shift grating is introduced, the modulation depth can be reduced to 3 × 10 ~ (-4), and its optical switch power threshold is also reduced to 210 MW / cm ~ 2.