Parameters affecting damage threshold in thin film infrared

Control of film deposition is important in determining the threshold of film damage due to a laser pulse. The optical properties of the infrared chalcogenide glass material T12SeAs2Te3 as process parameters are varied are reported. Several RF sputtered chalcogenide glass films of thicknesses varying from 0.6 micrometers to 8.9 micrometers were deposited on germanium and sapphire. The index of refraction and absorption coefficient were determined from the measured reflectance and transmittance curves for these samples. These properties were measured for two different sputtering pressures, two sputtering voltages, twelve azimuthal target positions and three different substrate to target distances. The damage due to switching was assessed by subjecting different switches to CO2 laser pulses with FWHM of 2 to 4 msec and energies up to 0.16 Joules which were focused on target spot diameter of 0.4 mm on the chalcogenide optical switch.