A reflective type liquid crystal optically addressed spatial light modulator has a first transparent substrate (1b), a first transparent electrode (2b) formed on the first transparent substrate (1b) and a photosensitive layer (3) formed on the first transparent electrode, formed from materials including hydrogenated amorphous silicon carbide (a-Si:C:H). A read-out light-blocking layer (4) is formed on top of the photosensor layer (3) and is formed from amorphous hydrogenated carbon (a-C:H). The high reflectance dielectric multilayer mirror (5) is formed on top of the light-blocking layer (4) and can be made of alternating the a-Si:C:H layers with a higher refractive index and the a-C:H layers with lower reflective index. The modulator also has a second transparent substrate (1a), a second transparent electrode (2a) formed on the second transparent substrate (1a), and a liquid crystal layer (8) disposed between the dielectric mirror (5) and the second transparent electrode (2a). The invention allows more efficient separation of the input and read lights and increases the read light reflection, resulting in improvements to the input sensitivity, resolution, contrast ratio, and diffraction efficacy.