Large and stable refractive index change in photochromic hybrid materials

We have developed new transparent photochromic hybrid organic-inorganic materials in which the photochromic group belongs to the polymer network. These materials involving chemically bonded dithienylethene derivatives were prepared by the sol-gel process in the form of thin films a few microns thick. The thickness and refractive index of the sol-gel films either at 633 or 785 nm were determined both in the colored and discolored state by using the attenuated total reflection (ATR) method. Functionalized sol-gel films showed a large refractive index change in a nonabsorbing spectral region: Delta n approximate to 4 x 10(-2) at 785 nm. This important variation due to the high photochrome content allowed us to design optical components used in the field of wave guiding.