Adaptive running hologram recording and phase-shift measurement in photorefractive crystals

The author reports the use of phase modulation techniques in two-wave mixing (2WM) experiments for measuring the phase shift psi between the interference pattern projected onto a photorefractive crystal and the resulting recorded hologram, as a function of the externally applied electric field E. Such data are used for computing the photoelectron trap density N/sub A/ in the crystal. Phase modulation techniques in conjunction with an adaptive fringe-locking method was also applied for running hologram recording under applied field E, which allows both matching of optimal recording conditions and measuring the 'resonance' hologram velocity v/sub o/. From v/sub o/ vs. E data, the diffusion length L/sub D/ and the photoelectron generation rate g/sub o/ are found and the quantum efficiency for the process may be computed. Experimental results for Bi/sub 12/SiO/sub 20/ (BSO) and Bi/sub 12/TiO/sub 20/ (BTO) are reported.<
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