Permanent Holographic Gratings for Wavelength Division Filtering
Final rept. 1 Jul 1996-30 Jun 2000
OKLAHOMA STATE UNIV STILLWATER
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The final report summarizes the major research accomplishments of this program. High quality glass samples have been grown with varying amounts of Eu2O3 and Al2O3. Glass fibers have also been made. A successful model of the grating kinetics that treats grating formation as the result of optically stimulated diffusion of small modifier ions was developed. Four-wave mixing FWM results indicate that the grating efficiency increases with both compositions, in agreement with our kinetics model. The FWM results show that the grating diffraction efficiency decreases with decreasing temperatures for Eu concentrations less than or equal to 10 mol. However, an increase in diffraction efficiency is observed for the Eu concentration of 15 mol. The grating efficiency is insensitive to temperatures above room temperature although the grating build-up time increases with higher temperature. The Raman and NMR dependence suggests an increase in NBOs and in 6-fold coordinated Al with increasing Eu, while a decrease in NBOs with an increase in 4-fold coordinated Al results with increasing Al. Ionic conductivity and Brillouin scattering measurements have also been performed. The effect of write beam and probe beam wavelengths on the formation of refractive index gratings in these glasses has also been studied. In addition, we have demonstrated the writing and recovery of holographic images in these glasses.