Research Of The Characteristics Of The Bismuth Silicate Photorefractive Spatial Light Modulators

The parallel computing capability and the boson property of the photon enables the optical parallel computing to be one of the late-model high-performance computing which will probably substitute the electrical computing in the future. The optically addressed spatial light modulators with high performance will be the cores of the two-dimension optical parallel information processing ststems, such as optical parallel computing systems and the optical pattern recognition systems.With some particular photo-electric and electro-optical properties, the photorefractive crystals, such as the bismuth silicate, have the functions of holographic memory, lightwaves coupling, all optical switch, wavelength conversion and incoherent-coherent conversion. When used the two-dimension optical parallel information processing ststems, the optically addressed spatial light modulators with the photorefractive crystals can work as a light detector and an electro-optical modulator at the same time. Furthermore, with excellent spectrum sensitivity and response speed, as well as the particular crystal lattice and photo-electric / electro-optical parameters, the bismuth silicate can make the research of the bismuth silicate spatial light modulators more convenient. Above all, the research results are useful for the research of the spatial light modulators based on other photorefractive crystals.When used in the two-dimension optical parallel information processing ststems, the spatial frequency response of the modulation transform function and the operation speed are the two key characteristices of the spatial light modulators. Some factors, which influence the spatial frequency response of the modulation transform function and the operation speed of the asymmetric reflective bismuth silicate spatial light modulator, are analysed in theory and experiment.Besides researching the image writing and reading of the asymmetric reflective bismuth silicate spatial light modulators, based on the band transport model, and the photoelectric damage of the BSO film obtained in the experiments is analyzed to achieve the transfer process and the final distribution of the charges inside the BSO film. Furthermore, the spatial frequency response of the modulation transform function of the asymmetric reflective bismuth silicate spatial light modulator is analysed and discussed in theory and experiment to achieve the intrinsic influence of the material properties, the structure parameters and the operation conditions on the spatial frequency response of the modulation transform function. The photoelectric damage can also provide some information of the growth of the bismuth silicate, and also indicate that the similar skin effect which usually occurs in the ac circuits and some ultrafast electric circuits have occurred in the BSO film while the charges are transferring.The characteristics of the photoinduced current, especially the characteristics of the discrete photoinduced current pulses of the asymmetric and reflective bismuth silicate spatial light modulator when in writing process are investigated in detail. How some of the electrical properties of the materials, the structure parameters and the operation conditions have influences on the current pulses are achieved. Fuethermore, the discrete photoinduced current pulses may also contribute to the photoelectric damage of the BSO film obtained under low light power, and the similar skin effect when the charges are transferring.Finally, based on the research results, the guide to optimize the asymmetric reflective bismuth silicate spatial light modulator by structure design, materials selection and the setup of operation modes and conditions is proposed.