Suspended silicon waveguides for long-wave infrared wavelengths

TL;DR

This paper demonstrates the first low-loss suspended silicon waveguides operating at 7.67 mm wavelength, achieving propagation losses comparable to other platforms, enabling long-wave infrared integrated photonics.

Contribution

It introduces a novel suspended silicon waveguide design supporting long-wave infrared wavelengths with low propagation loss and effective bend structures.

Findings

Propagation loss of 3.1 ± 0.3 dB/cm at 7.67 mm

Successful fabrication of low-loss waveguide bends and s-bends

First demonstration of silicon waveguides at such long wavelengths

Abstract

In this paper we report suspended silicon waveguides operating at a wavelength of 7.67 mm with a propagation loss of 3.1 ? 0.3 dB/cm. To our knowledge this is the first demonstration of low loss silicon waveguides at such a long wavelength, with loss comparable to other platforms that use more exotic materials. The suspended Si waveguide core is supported by a subwavelength grating that provides lateral optical confinement, while also allowing access to the buried oxide layer so that it can be wet etched using hydrofluoric acid. We also demonstrate low loss waveguide bends and s-bends.