Thermo-optic coefficient in some hybrid organic/inorganic fast sol–gel glasses

✍ Scribed by M. Pokrass; Z. Burshtein; R. Gvishi

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 426 KB
• Volume: 32
• Category: Article
• ISSN: 0925-3467
• DOI: 10.1016/j.optmat.2010.01.038

✦ Synopsis

We have investigated the effect of organic content in hybrid organic/inorganic glasses prepared by the sol-gel process on the thermo-optic coefficient dn/dT. The organic phase consisted of homogeneously dispersed methyl groups within an inorganic silica matrix. Analysis of Fresnel reflectance temperature dependence of an optically polished sample-surface yielded the desired value, with an accuracy of 10 À5 /°C. A negative linear dependence of the thermo-optic coefficient on the volumetric thermal expansion coefficient b was obtained, dn/dT[10 À4 /°C] = À1.1-0.45b[10 À4 /°C]. Using Prod'homme's model, a negative value was derived for the electronic polarizability coefficient U = (À1.8 ± 0.3) Â 10 À4 /°C. The negative sign of U is attributed to isolation of the silica matrix sections by the methyl groups, causing the sections to distance upon increase in temperature.