A method of measurement of the optical absorption coefficient for a semiconductor sample is given, based on the simplified pattern by Rosencwaig and Gersho in the particular case of thick samples. This method allows us to deduce directly the absorption coefficient from photoacoustic amplitude signal measurement, whatever the incident light modulation frequency. The experimental results obtained from thicker sample of GaP (0.2–1 mm) are compared with the results given by classical optical methods.
J. Fesquet, B. Girault, and M. D. M. Razafindrandriatsimaniry, "Determination of absorption coefficients of thick semiconductor samples using photoacoustic spectroscopy," Appl. Opt. 23, 2784-2787 (1984)