Fabrication of photonic crystal structures in polymer waveguide material

Abstract

In this paper we show some aspects of the fabrication of photonic crystal (PC) structures in a polymer waveguide material on different waveguide substrate materials. The photonic structures consist of a slab waveguide perforated by a periodic arrangement of sub-micron high aspect ratio holes with typical hole diameters of 300 nm at periods of 500 nm and a depth of down to 4 μm. The patterns were written by an electron beam writer in an e-beam resist, then transferred into a NiCr-hard mask and etched in the polymer waveguide by means of an electron cyclotron resonance (ECR) high density plasma system. For the waveguide the polymer PMMA-DR1 was used and for the waveguide substrates, materials with different refractive indices (Teflon and an ultra low refractive index “air like” material) were investigated. PCs made in polymer on ultra low “air like” index substrate are easier to fabricate and show higher transmission efficiency and higher Q-factor compared to those made in polymer on Teflon.