Abstract

Recently the wavelength dependence of the photorefractive effect has been receiving considerable attention.¹ We report the wavelength dependence of degenerate four-wave mixing in a home grown and a commercial bismuth silicon oxide (BSO, Bi₁₂SiO₂₀) crystal. The beam from a line tunable multiaxial mode Ar⁺ laser in the TEM₀₀ mode is divided into three beams, which meet in the sample in a standard configuration, with two counterpropagating pump beams of equal intensity, and one probe beam fifteen times weaker. The probe and one pump have equal path lengths to the sample. The signal is recorded with the help of a monochromator, a photomultiplier tube operated in the linear region, an amplifier and a recorder. The wavelength of the laser and the monochromator are tuned together. The intensity of all three beams are kept fixed at all wavelengths. In the wavelength region investigated (457-514 nm) the intensity of signal (arbitrary units) is zero up to ~476 nm and then rises linearly to ~150. The photorefractive grating in the commercial crystal shows single growth and decay times, whereas the home grown sample shows two growth and decay times.

© 1991 Optical Society of America