Laser induced phenomena in γ -glycine crystals

The photoinduced changes of absorption within the spectral range 200–800 nm and optical second harmonic generation caused by illumination by the cw second harmonic generation of the Nd:YAG laser (λ = 532 nm) and power about 400 mW were investigated. We have established that increasing the time of illumination by the second harmonic generation of the Nd:YAG laser leads to the occurrence of one strong spectral minimum at 319 nm and another less strong at 420 nm. Increasing the time of illumination leads to a slight red spectral shift of the photoinduced minima. The absence of a substantial increase in temperature indicates that the principal role is played here by the photooccupation of the trapping levels. The effect is observed in a wide spectral range of the incident photoinduced angles, however, the beam should possess a good Gaussian-like form and to be space homogenous. The results were reproduced with precision up to 3–4% which was achieved due to additional stabilization of the photoinduced laser power by double control of the power.