The photorefractive effect in semiconductors

摘要: The majority of experimental work on the fundamentals and applications photorefractive effect has been carried out with ferroelectric oxides. These materials have strongest known electro-optic effects, which in turn lead to largest index changes. However, magnitude electrooptic alone is not sufficient characterize a material for all applications. It was realized many years ago [8.1 ] that maximum sensitivity (index change per absorbed photon density) it necessary maximize ratio coefficient dielectric constant photocarrier drift or diffusion length comparable fringe spacing phase hologram. For these reasons, efficient photoconductors such as bismuth silicon oxide (BSO) can be useful even more than ferroelectrics optical processing applications, though BSO relatively small. perhaps surprising passed after initial demonstration photorefraction [8.2] before any attention paid semiconductors are common use other opto-electronic Optically induced changes had observed CdS [8.3] soon discovery "optical damage" LiNbO3. Although observations were made full understanding obtained, effects found origins. In this chapter various characteristics make them will discussed. underlying theory already discussed elsewhere volume reader referred those sections details. At present time, only few experiments using described literature [8.4-8] so major emphasis placed studied; namely, InP GaAs. Other from point view their potential where appropriate, but principles remain same.