Abstract

In a search for all-optical signal processing elements operating at a picosecond time scale nonlinear phenomena in quadratic media, extensively studied since many years in a different context were revisited lately. However, all devices proposed and implemented to date (see [1,2] and Refs, therein) have certain drawbacks complicating their use as all-optical amplifying/switching devices, viz., low amplification because of a strong control signal in intensity-controlled devices, smooth switching characteristics of Mach-Zehnder interferometers, and a requirement of fast phase control in phase-sensitive devices [3]. A key requirement of all devices proposed until now is the coherence of pump and signal beams because the χ⁽²⁾-process strongly depends on the relative phase. Here we demonstrate that this phase-insensitive amplification/switching can be achieved by a three wave interaction even with reduced pump power requirements. In what follows we focus on the so-called vectorial or type II SHG where two orthogonally polarized fundamental frequency (FF) components A₁ and A₂ interact with the only second harmonic (SH) wave B polarized parallel to one of the fundamentals [2].

© 1997 Optical Society of America