Germanium-Based Mid-Infrared Photonics

TL;DR

This paper reviews recent advances in germanium-based photonic integrated circuits for mid-infrared applications, highlighting material platforms, device developments, sensing demonstrations, and future challenges for industrial deployment.

Contribution

It provides a comprehensive overview of the state-of-the-art in Ge-based mid-IR photonics, including recent progress and remaining challenges for practical applications.

Findings

Demonstrated sensing capabilities in Ge-based mid-IR devices

Identified key material and device challenges for commercialization

Reviewed various active and nonlinear photonic components

Abstract

The mid-infrared (mid-IR) spectral range is a part of the electromagnetic spectrum in which most of the molecules have vibrational and rotational resonances. Ge-based photonic integrated circuits in this wavelength range have thus seen a burst of interest in the recent years, mainly driven by applications related with the detection of chemical and biological substances. Here we review the motivations and the recent developments in this field, from the different material platforms to active and nonlinear devices. We also discuss a few demonstrations of sensing that have already been conducted, attesting the potential applications of such devices. Finally, we conclude by discussing the challenges that have to be solved to transition from lab demonstrations to practical industrial devices.