Evaporated polyurea optical waveguides: electrooptic and structural properties

Abstract Electrooptically active planar waveguides of aromatic polyurea were prepared by simultaneous deposition of 4,4′-diamino-diphenyl-methane and 4,4′-diphenylmethane-diisocyanate from the vapor phase and subsequent corona poling. X-ray diffraction spectra show that part of the films has a pronounced layered structure reminiscent of self-assembling systems. Attenuated total reflectance spectroscopy of the waveguide modes of the polymer films was used to measure the piezoelectric and electrooptic susceptibilities. The contributions of the nonlinear polarizability of the urea groups and their dipolar orientation in the applied field are identified. Possible applications of this material for novel optical modulator geometries are discussed.