High confinement, high yield Si3N4 waveguides for nonlinear optical application

TL;DR

This paper introduces a new fabrication method for high-thickness silicon nitride waveguides that reduces stress-induced cracks and achieves low propagation losses, advancing nonlinear optical device development.

Contribution

A novel trench-filling fabrication technique for thick Si3N4 waveguides with high yield and low losses suitable for nonlinear optics.

Findings

No stress-induced cracks observed in fabricated waveguides

Propagation losses as low as 0.4 dB/cm at 1550 nm

High device yield on wafer

Abstract

In this paper we present a novel fabrication technique for silicon nitride (Si3N4) waveguides with a thickness of up to 900 nm, which are suitable for nonlinear optical applications. The fabrication method is based on etching trenches in thermally oxidized silicon and filling the trenches with Si3N4. Using this technique no stress-induced cracks in the Si3N4 layer were observed resulting in a high yield of devices on the wafer. The propagation losses of the obtained waveguides were measured to be as low as 0.4 dB/cm at a wavelength of around 1550 nm.