SPATIOTEMPORAL STRUCTURE FORMATION AND SELF-DIFFRACTION IN CDS USING LASER-INDUCED THERMAL GRATINGS

The semiconductor CdS is well known to show various kinds of photo-thermal and photo-electric optical nonlinearities. We present here to our knowledge first results of spatio-temporal structure formation using laser-induced thermal gratings in CdS. By the means of an optical multi-channel analyzer the spatial resolution of transverse dynamic switching processes was observed directly. Spatially and time resolved self-diffracted signals were measured in the far-field. The experimental results agree very well with calculations obtained by solving the heat-flow equation and using a fast Fourier transformation. The calculations verify the experimental parameters, in particular the thermal diffusivity D almost-equal-to 0.1 cm2/s at room temperature. To obtain a better transverse structuring, CdS samples were also investigated which were fixed on a sapphire substrate for longitudinal heat sinking.