Fabrication of silicon vertical taper structures using KOH anisotropic etching

Abstract

In order to exploit the full potential of silicon photonic devices we require an efficient way of coupling light from fibres to integrated photonic circuits. One of the most common solutions to this problem is the use of tapered silicon waveguides. We present a method of vertical silicon taper fabrication using KOH anisotropic etching of a silicon wafer with tilted 〈1 1 1〉 crystallographic orientation. The main advantage of this method is the low roughness of the tilted surface, which should lead to a good optical transmission of the tapered waveguide.