Addition of Hetero-Atoms to the Polymer Film by Plasma Enhanced Polymerization and its Optical Properties

Abstract

Plasma enhanced polymerization is an attractive technology to fabricate an optical polymer waveguide, because it has capability to provide an uniform thickness film on a substrate with various surface geometry, and to provide change of refractive index by controlling a proportion of source monomer mixing. In the present paper we discuss optical constants and molecule structures of the films added hetero-atoms, O, N and F in the CH_x network of polymer. Refractive index of those films changes from 1.52 to 1.63 at 1.0 μm wavelength, depending on the variety of hetero-atoms. Fluorine atoms added into a film decreases refractive index of the film. Oxygen atoms added into a film, which form ester structure (- COO-), decrease refractive index of the film, and some O atoms token into a film as OH base will increase optical absorption in inferred region for optical communication. Nitrogen atoms added increase optical absorption due to forming NH₂ base. Finally, sp³/sp² fraction controlling in the film will be a suitable to control refractive index of the film for an optical waveguide, for example by using mixed monomer of C₆H₆ and C₆H₁₀.