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Stimulated emission from silicon-nanocrystal planar waveguides grown via phase separation and thermal crystallization of SiO/SiO2 superlattices is presented. Under high power pulsed excitation, positive optical gain can be observed once a good optical confinement in the waveguide is achieved and the silicon nanocrystals have proper size. A critical tradeoff between Auger nonradiative recombination processes and stimulated emission is observed. The measured large gain values are explained by the small size dispersion in these silicon nanocrystals. [ABSTRACT FROM AUTHOR]

CeO2/Sm2O3 multilayer films were deposited on p-type Si wafers by e-beam evaporation technology. Four typical photoluminescence peaks of Sm3+ ions located around 572, 615, 656, and 719 nm were observed after the samples were annealed in an oxidizing atmosphere at high temperature. The luminescence properties of CeO2:Sm3+ films were characterized by excitation, emission spectra, and decay curves. In addition, a study of the effects of Sm2O3 thickness and annealing time on the samples' photoluminescence was conducted. [ABSTRACT FROM AUTHOR]

We investigate the optical properties of planar waveguides where the core layer is formed by a silicon nanocrystals (Si-nc)/SiO2 superlattice. M-line measurements of the different waveguides yield the mode indices, which can be modeled by assuming anisotropic optical properties of the core layer. This anisotropy is related to the superlattice, i.e., it is a form birefringence. By modeling the m-line measurements with the structural data obtained by transmission electron microscopy analysis, we determine for each waveguide the value of the form birefringence, an upper limit of the nanocrystals size and their refractive index. Values of the form birefringence as high as 1% have been found. [ABSTRACT FROM AUTHOR]

Amorphous SiO/SiO[SUB2] superlattices were prepared by reactive evaporation of SiO powder in an oxygen atmosphere. Infrared absorption and photoluminescence spectra were measured as a function of annealing temperature. Three photoluminescence emission bands were observed. A band centered at 560 nm is present in as-prepared samples and vanishes for annealing above 700 °C. The second band around 760 nm to 890 nm is detected for annealing temperatures above 500 °C. A strong red luminescence is observed for annealing temperatures above 900 °C. The origin of the different photoluminescence bands and different states of the phase separation of ultrathin Sio[SUBx] layers is discussed. [ABSTRACT FROM AUTHOR]