One-dimensional steady-state photorefractive spatial solitons in centrosymmetric paraelectric KLTN

摘要

Photorefractive spatial solitons have been the subject of intense study over the past few years. They have been predicted and observed in quasi-steady-state, steady state in photovoltaic materials, the steady-state screening configuration, and photorefractive semiconductors. More complicated phenomena have also been reported, giving rise to a wealth of intriguing observations, such as self-trapping of incoherent white-light beams and soliton-soliton interactions. All these have been observed in noncentrosymmetric materials, where soliton formation is brought about by a change in the refractive index due to the linear electro-optic response to an internal photoinduced space charge field. Recently, spatial screening solitons of a different nature than should exist in photorefractive centrosymmetric materials have been predicted. Here, we report the first observation of such solitons in paraelectric (centrosymmetric) KLiTaNbO/sub 3/ (KLTN) and compare our experiments to the theoretical predictions. Centrosymmetric screening solitons are generated by the index modulation produced by the quadratic electro-optic response to the photorefractive internal photoinduced field.