Holographic volume absorption grating in glass-like polymer recording material

We present investigations of glass-like polymer recording mediums based on poly(methyl methacrylate) (PMMA) and its thermostable derivative (copolymer with acrylic acid) (PMMA+AA) with regard to their application as storage materials for holographic gratings. We have estimated the contribution of the absorption gratings to the total diffraction efficiency (DE) of holographic gratings in these materials. The absorption gratings are faster generated than the phase gratings. The absorption of the recording media decreases under illumination and increases by heating. The maximal DE was 2% (0.5%) for the absorption grating and 32% (22.5%) for the phase grating in PMMA+AA (PMMA). The refractive index modulation covers the range of 10-4-10-3 during recording. During heating the DE of the absorption grating can reach 2% for PMMA, while the absorption grating in PMMA+AA is not essential. The total DE in saturation is about 10% for both polymers.