Temperature-insensitive strain measurement using differential double Bragg grating technique

The compositional dependence of the optical constants, the refractive index n, and the absorption index k, of the AsSei-xTe.v thin films with 0 < x < 1.0 were determined in the spectral range of 400-2500 nm. The maximum value of the refractive index n, is shifted toward the long wavelength by increasing the Te content in the examined system. The values of the forbidden energy gap of the system have been determined and were correlated with the type and the amount of chemical bonds formed by the increasing Te content in the AsSei-yTe.x glassy system. The value of the dispersion energy E^ exhibits low value at the composition containing the same atomic percent of Se and Te.