Investigation of the optical losses in infrared-optics materials by a laser optoacoustic method

A demonstration is given of the feasibility of determining optical losses in highly transparent infrared-optics materials by a laser optoacoustic method. It is shown that under certain conditions the recorded acoustic signals are independent of the experimental geometry and of the parameters of the probe radiation. Experiments are reported in which the scattered radiation can be detected down to energies E_min = 0.3 μ J and the absorption down to α_min E_o = 0.1 μ J/cm. The results are given of an experimental investigation of the losses in n- and p-type Ge, and in KRS-5 and KRS-6 crystals (absorption at the level 10^–4 cm^–1 ) with the aid of a pulsed CO₂ laser.