Achromatic grating two-wave mixing in photorefractive BaTiO 3 using an amplitude-modulated laser diode

Laser diodes are becoming increasingly important in ground and space-based communication systems. The laser power can be modulated at frequencies up to gigahertz to allow extremely high bandwidth communications. Nonlinear optical devices such as photorefractive crystals have been proposed for use in such optical networks for power amplifiers and active beam cleanup devices. One problem with the use of nonlinear optics techniques such as two-and four-wave mixing with laser diodes is that high-frequency modulation of the drive current can widen the laser linewidth enormously.1 Thus a technique is required that will allow wave mixing with a wide bandwidth or multiple-frequency source.