Optimal Properties Of Photorefractive Materials For Optical Data Processing

Abstract

The charge transport model of photorefractivity is used to evaluate four figures of merit that can be employed to characterize the performance of photorefractive materials. The figures of merit are the steady -state index change, the response time, the energy per area to write a grating with 1% diffraction efficiency, and the index change per absorbed energy per unit volume (photorefractive sensitivity). These indices are evaluated as a function of grating period and applied external electric field for Bi12Si020, a fast-material with a relatively small electro -optic coefficient, and BaTiO3, a slower material with a much larger electro -optic coefficient. Methods for optimizing the materials are discussed.

Structure and optical properties of near stoichiometric Ce:LiNbO3 crystals

“…It is known that the writing time is inversely proportional to the photoconductivity σ ph according to the equation: [21], the writing time increases with the photoconductivity σ ph decreasing, so the writing time of SLN-1 is shorter than that of SLN-2. In the same way, the high concentration of the intrinsic defects in CLN-0 make the writing time of CLN-0 much longer than that of SLN-0.…”

Two-beam coupling measurements of grating phase in a photorefractive polymer

“…26 the space charge field generated leads directly to an index grating. Further, the phase of the space charge field (and thus the phase of the index modulation) may be calculated using the complex form for l!…”

L'effet photoréfractif

“…En régime d'excitation impulsionnelle [64][65][66][67], de nombreux phénomènes qui n'interviennent pas en régime d'excitation continue doivent être pris en compte. Par exemple, si des niveaux superficiels (près de la bande de conduction) existent, alors ils modifient la cinétique de l'effet photoréfractif [64], L'effet photoréfractif peut également se mélanger à d'autres phénomènes optiques non-linéaires tels que absorption induite, non-linéarités dues aux porteurs libres [65]... Nous donnons donc la résolution suivante en tant qu'illustration et à titre indicatif.…”