Conversion of optical signals in a laser with an intracavity liquid-crystal spatial modulator

Image of amplification by a factor of ~10⁵ and an increase in the contrast by a factor of 10³ were achieved by intracavity image readout from spatial light modulators. Two types of photosemiconductor–liquid crystal modulators were used: 1) utilizing a cholesteric–nematic phase transition; 2) utilizing the electrooptic effect in a nematic liquid crystal. The image quality was at the diffraction limit both for a dye laser and a YAG:Nd³⁺ laser; the sharpness of the image boundaries and the contrast increased above the lasing threshold. When readout took place from an area of the diffraction-limit size in a free-running YAG:Nd³⁺ laser, the radiation energy was 0.8 × 10^–3 J and the energy density reaching the modulator was ~1.4 J/cm² (the energy of the recording light of the λ = 0.44 μ wavelength was ~0.4 × 10^–8 J and the energy density in the recording stage was ~10^–6J/cm²).