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    Photorefractive Effect in an Imperfect Cerium Doped Barium Titanate Crystal: Reflection Grating Case
    (2026-01-01)
    Khotphuthon, Wasuphon
    ;
    Plaipichit, Suwan
    ;
    Suchat, Suebtarkul
    ;
    Buranasiri, Prathan
    The photorefractive (PR) effect, a nonlinear optic phenomenon, occurs in materials that have electro-optic (EO) properties. When two coherent beams of light interfere with each other in a PR material, donor electrons between valence band and conduction band, caused by material impurity, absorb the photon and are excited into the conduction band and generate electron-hole pairs. This process induces a periodic electric field called a space charge field that alters the material’s refractive index due to the EO effect. In this research, we explored reflection grating (RG) in an imperfect Ce-doped BaTiO3 crystal and then showed optical image correlation using the RG. Two beam coupling was investigated using two non-Gaussian incident beams on the opposite surface of an imperfect Ce-doped BaTiO3 crystal. Light at green wavelengths from a semiconductor laser was used as the source of the incident beams and entered at certain angles relative to the crystal c-axis. Large beam coupling power was observed in both incident directions when the angle between both incident beams is at Bragg’s angle in the direction of the c-axis. The diffraction light was found to be in the same polarization as the incident beam. In addition, interesting results for the optical correlation using reflection grating were demonstrated. These results suggest that by doping BaTiO3 with cerium, strong beam coupling or photorefractive grating can be observed with certain incident writing angles on the crystal, which could be utilized in future flexible holographic devices in the future.
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    The generation of optical phase conjugation from cerium doped barium titanate at wavelength of 632.8 nm
    (2013-09-18)
    Sidakum, K.
    ;
    Buranasiri, P.
    ;
    Plaipichit, S.
    ;
    Ruttanapun, C.
    ;
    Jindajithawat, P.
    In this paper, optical phase conjugate beam with the using of different resonator configurations has been investigate. Two types of SPPC resonators were selected to use, the first one is linear resonators formed by crystal surface and the other one is linear resonators formed by single mirror and a photorefractive crystal. In our experiment, cerium doped barium titanate crystal (BaTiO3: Ce) and He-Ne laser with wavelength of 632.8 nm have been used. From the results of both cases, the angle of the incident beams is optimum at 37.95° respect to the normal line of the surface that parallel to the c-axis of the crystal. The generating time of OPC beam are 150 seconds and 330 seconds for the first and second type resonators, respectively. The reflection ratios are equal to 8.75% and 5% for the first and second type resonators, respectively (the first type resonators could provide better reflection ratio). © 2013 SPIE.
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    Multi high-order anisotropic self-diffraction in Cerium doped BaTiO 3 crystal
    (2012-03-23)
    Plaipichit, S.
    ;
    Buranasiri, P.
    ;
    Nuansri, R.
    ;
    Neeyakorn, W.
    Higher-order anisotropic self-diffraction up to third orders have been observed in Cerium doped barium titanate by using red beam at 633 nm from He-Ne laser. In our experiment, the third orders and second orders have been observed simultaneously for the first time from our knowledge. From our observation, the phase conjugate beam has not been generated before and after the appearance of higher orders as observing when the green beam from the Argon-ion laser at 514.5 nm has been used. The diffraction efficiency and the decay rate of the grating have been measured as well in the red light case. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).