CMOS-compatible Si3N4 Waveguides for Optical Biosensing

Abstract

We present a CMOS-compatible silicon nitride (Si3N4) waveguide technology platform suitable for monolithic co-integration with optoelectronics in the visible and <1.1μm near infrared wavelength region. With an optimized fabrication process employing low-temperature plasma enhanced chemical vapour deposition (PECVD) and reactive ion etching (RIE), propagation losses of 0.86dB/cm were achieved at λ=850nm for wire waveguides with a cross section of 600x250 nm2. As an example of application we show Mach-Zehnder interferometer based label-free optical detection of the S-protein/S-peptide interaction. Moreover, we present experimental steps towards the realisation of multi-channel biosensors using spiral shaped waveguide structures ensuring a small form factor.