Laser calorimetry as a tool for the optimization of mid-infrared OPO materials

A new laser calorimetric technique has been developed to enable absorption, transmission and heat capacity measurements to be made on arbitrarily shaped crystals and other optical materials. Samples are mounted inside a unique cradle device, which ensures minimal heat exchange with the sample's surroundings. A transmission map of the sample is formed by moving the sample, under computer control, through a fixed laser beam. The absorption of the sample at specific points is obtained by recording the temperature rise of the sample due to heating by the laser beam. Spatially resolved measurements are reported for a number of materials including ZnGeP2 and quasi-phase matched GaAs, and correlated with transmission characteristics obtained using a mid-IR band InSb camera.