Optimization of the Structural and Optical Properties of Ge-As-Se Glasses

In this study Ge_XAs_ySe_100x+y glasses with 0lesx<40 and 12lesy40 are characterized to determine the effects of varying composition on parameters such as the nonlinear refractive index (n₂), glass transition temperature (T_g) and the optical absorption band edge (E_g). The linear absorption losses were studied using photo-thermal deflection spectroscopy (PDS). We found that increasing the Ge concentration increases the linear absorption loss, ranging from ~ 0.05 dB/cm for Ge₅As₃₈Se₅₇ to > 0.1 dB/cm for Ge > 33% (Ge₃₃As₁₂Se₅₅) at 1550 nm. A modified Z-Scan technique was developed to measure the nonlinear refractive index (n₂) at 1500 nm. The conventional closed aperture is replaced by an InGaAs camera to image the output beam. Image analysis is done using Lab VIEW software and the on axis transmission is measured and extracted as a Z-scan.