Plasma-deposited fluorocarbon coatings for passive and active integrated optical devices

Abstract

Amorphous fluorocarbon polymers are attractive materials for optical applications because of their high transparency at wavelengths up to 3 micrometers because of the absence of C-H bonds. since 1989 DuPont's amorphous fluoropolymer Teflon AF is available, films of which can be fabricated by means of spin, spray, or dip coating from solution or by use of compression or injection molding from the melt. An alternative and promissing route for processing fluorocarbon films is the use of a low- pressure plasma: This technique can be employed for plasma polymerization of suitable fluorocarbon monomers and for controlled etching of fluorocarbon materials. In the present work, we present the characteristics of plasma-polymerized tetrafluoroethylene layers with a refractive index of approximately 1.4. Reactive ion etching in an N2O plasma is used for patterning these layers, and also the spin-coated Teflon AF films with a refractive index of around 1.3. Possibilities of fabricating passive and active polymer waveguide devices from flurocarbon polymers are discussed, and estimates of the expected waveguide performance are presented.