Electro-optic frequency comb generation in the mid-infrared.

Introduction

Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances and to perform non-invasive diagnostics. More specifically, the 6-15 µm wavelength range can be exploited to detect small traces of environmentally hazardous and toxic substances for a variety of applications including defense, security, and industrial monitoring.

Current Challenges

While current optical systems in the mid-IR range are based on bulky assemblies of discrete devices, a challenging task is to make mid-IR spectroscopy accessible in remote areas. This drives the development of compact and cost-effective solutions to replace table-top systems.

Project Goals

In the project, we aim at addressing new routes for high-resolution spectroscopic systems based on dual-comb spectroscopy by developing innovative frequency comb sources.

Strategy

The strategy developed in ELECTROPHOT is based on the unique properties of graded index Silicon Germanium (SiGe) photonics circuits. These properties include:

• Transparency in a wide spectral range
• Ability to fine-tune both the electronic bandgap and refractive index of SiGe alloys

This approach aims to make large progress in mid-IR photonics.

Original Idea

Based on these capabilities, the original idea of the project is to exploit simultaneously optical nonlinear and electro-optic comb generation. This will generate compact frequency comb sources that provide:

1. Wideband operation
2. Fine and tunable resolution

Fabrication Technologies

Interestingly, the photonics circuits will leverage reliable and high-volume fabrication technologies, which have already been developed for microelectronic integrated circuits. This provides a new playground in mid-IR photonics.