On-chip pulse generation at 8 {\mu}m wavelength

TL;DR

This paper presents an integrated silicon-germanium photonic approach to generate ultrashort pulses around 8 micrometers, advancing mid-infrared laser source integration for sensing applications.

Contribution

It introduces a novel on-chip pulse generation method using chirped Bragg gratings to compensate dispersion in quantum cascade laser frequency combs.

Findings

Achieved 1.39 ps pulse duration at 8 μm wavelength.

Demonstrated dispersion compensation with engineered gratings.

Enabled potential for fully integrated mid-infrared ultrashort pulse sources.

Abstract

The mid-infrared spectral region holds growing importance for applications such as gas sensing and spectroscopy. Although compact ultrashort pulse laser sources are essential to enable these applications, their realization in this spectral range remains an open challenge. We demonstrate an integrated approach to generate pulses in the mid-infrared based on chirped Bragg gratings engineered to compensate for the group delay dispersion of quantum cascade laser frequency comb sources. SiGe graded-index photonic circuits are used for operation around 8 {\mu}m wavelength. With this approach, pulses as short as 1.39 picoseconds were obtained, marking a key step towards fully integrated ultrashort pulse sources in the mid-infrared.