Holographic diffraction gratings recording in organically modified silica gels.

The silica gel-methyl methacrylate organically modified ceramic is proposed for recording of volume holograms. Both low-spatial-frequency (54 line pairs/mm(-1)) and high-spatial-frequency (1400 line pairs/mm(-1)) holographic gratings were successfully recorded in the medium by interference of two coherent beams of 351.1-nm wavelength. High diffraction efficiencies (93%) and extremely low absorption and scattering coefficients were measured during the holographic reconstruction by a 632.8-nm He-Ne beam. The optimum UV recording exposure was ~3 J cm(-2). A grating refractive-index modulation amplitude of 1.1 x 10(-4) was achieved. Virtually no changes in diffraction efficiency were observed after thermal-heating, light-curing, and long-term-aging experiments.