Thin Films of Organic Salts with Large Optical Non-Linearities by Organic Vapor Phase Deposition.

Abstract

Recently, single crystals of organic and organometallic salts1-3 have been shown to possess extremely large second order (χ(2)) NLO effects leading to a high second harmonic generation (SHG) efficiency. The naturally non-centrosymmetric crystal structures of these compounds eliminates the need for external poling as required for guest-host polymeric systems. Furthermore, these salts have a high optical damage threshold and sufficient stability with respect to temperature to withstand many conventional semiconductor fabrication processes. In particular, highly pure single crystals of the salt, 4'-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST)1, have been shown to have a value of χ(2) at least 103 times greater than that of urea.