Measurement of thermooptic coefficients dn/sub E//dT and dn/sub O//dT of AgGaS/sub 2/ at 308 and 97 K

Thermooptic coefficients (dn/sub E//dT and dn/sub O//dT) of AgGaS/sub 2/ have been measured at temperatures of /spl sim/308 and 97 K, using temperature-induced shift in the frequency of the interference fringes in the Fourier transform infrared (FTIR) transmittance spectrum of a 2-mm-thick etalon. Values of dn/sub E//dT and dn/sub O//dT are reported for the spectral regime from 12.4 /spl mu/m to 1.06 /spl mu/m; the subscripts E and O refer to extraordinary and ordinary rays, respectively. Our values of dn/sub E//dT and dn/sub O//dT at 308 K are significantly lower (/spl sim/1/3) than those reported previously.