The theory of thegeneration of second harmonic of the nonlinear photoacoustics signal of the optical inhomogeneous solids
The theory of second harmonic (SH) nonlinear PA - signal optically inhomogeneous and semi transparences solids has been presented. Depending on the amplitude and phase of the signal from the frequency modulation of the incident beam and thermal coefficient (TC) of thermal and optical parameters for most of interest cases are obtained.