OPTICAL-PROPERTIES OF CDS NANOCRYSTALLITES EMBEDDED IN (SI0.2TI0.8)O-2 SOL-GEL WAVE-GUIDE

We report on the implementation of a two-grating coupler technique for measurement of repopulation of deep traps in CdS nanocrystallites emb edded in a (Si0.2Ti0.8)O-2 waveguiding glass layer of high refractive index. A sol-gel process is used to produce this waveguide. The low at tenuation (similar to 1 dB/cm) of the waveguide allows to in-and out-c ouple light by surface relief gratings embossed on the top layer of th e waveguide. The spectral region of waveguiding (approximate to 700 nm ) that was studied corresponds to the deep trap spectral position in C dS. The waveguiding beam is used as a probe beam and we used the third harmonics of a YLF:Nd laser (347 nm) as a pump. The influence of bimo lecular recombination on repopulation of deep traps is demonstrated, T he linear recombination time as well as bimolecular and Auger coeffici ents are determined. (C) 1998 Elsevier Science B.V.