Resonant two-photon absorption in ZnSiP2

The complex of optical investigations into the intrinsic (I) and resonant (R) two-photon absorption (TPA) inZnSiP 2 crystals of tetragonal modifications is performed by methods of amplitude laser-modulation spectroscopy. The ITPA of allowed-forbidden type and the two Lorentz spectral lines associated with coherent resonant two-photon transitions through impurity states of allowed-allowed type are found. The electron transverse relaxation time at the RTPA is determined, and the total absorption cross section of laser-radiation photons emitted at electron transitions between the valence band v, the conduction band c, and local centers that produce real states intermediate for the RTPA in the forbidden band is estimated.