Abstract

Optical spatial solitons, in particular photorefractive solitons, have been investigated extensively in the past few years¹. Recently photorefractive “bright solitons” were observed also in lithium niobate by applying appropriate external electric fields on the crystals. A ‘‘bright soliton’’ is a light beam which does not diffract and remains confined within a channel of the order of tens of microns. Thanks to the bias electric field, bright solitons can be induced by a continuous wave light beams with powers as low as a few microwatts. Up to now, soliton fonnation and evolution has been widely studied, even if the attention has been focused only on the intensity light distribution². In fact direct measurement of soliton phase lias not been ever performed.

© 2007 IEEE