Optical Second Harmonic Generation from Poled Thin Films of Aromatic Polyurea Prepared by Vapor Deposition Polymerization

Abstract

We have observed second-harmonic generation (SHG) in poled thin films prepared by the vacuum evaporation technique for the first time. We have shown the high potential of poled aromatic polyurea prepared by vapor deposition polymerization as SHG devices: (1) fairly high nonlinear susceptibility, i.e., χ z z z (2) =8.0×10 -9 esu (3.4 pm/V) and χ z x x (2) =2.2×10 -9 esu (0.92 pm/V): (2) wide transparent range down to 400 nm: (3) well controllable film thickness: (4) high T g and negligible relaxation; and (5) the possibility of a variety of main-chain structures.