All-optical steering of spatial solitary-waves through cascading in KTP

Abstract

Solitary-waves of the quadratic nonlinearity have been recently revisited due to the renewed interest in coherent effects via second-order cascading [1-3] and the experimental observations of spatially confined field distributions in bulk KTP crystals. [4-5] Most investigations, however, have dealt primarily with such waves in the framework of scalar interactions between fields at the involved frequencies. [6-9] In this Communication we report on the angular steering of solitary waves formed in 2+1 dimensions through a vectorial or Type II Second Harmonic Generation (SHG) process in a bulk crystal of KTP. Steering was already observed with similar soliton-like waves in KTP by injecting a coherent SH seed of specified input phase.[5] On the contrary, we are able to control the beam lateral displacement after propagation by acting upon the relative intensities of two orthogonally-polarized input fields at the fundamental frequency (FF), i.e. without resorting to a phase controlled input at the second harmonic. Such an approach to phase-insensitive steering of two-dimensional solitary waves allows the implementation of reconfigurable interconnects through an input intensity imbalance at the (fundamental) frequency of relevance, eliminating the need for an additional (coherent) signal at the SH.