Photorefractive Gratings Induced in KNbO3 by Picosecond Light Pulses.

摘要

Photorefractive gratings have been generated in KNbO3 crystals using 532 nm 30 ps laser pulses in a degenerate four-wave mixing experiment. The results show the grating comprises two components; a conjugate peak associated with the third-order susceptibility of the coincident optical pulses and a photorefractive component lasting for several nanoseconds. The rapid formation of the photorefractive component indicates the charge carriers are trapped within 100 ps. Calculations show that a mechanism associated with a relaxation mode of the Nb(5+) ions hopping between potential wells in the unit cell may be contributing to the observed intensity of the conjugate peak. Reprints. (JHD)