Mid-infrared quantum cascade laser frequency combs based on multi-section waveguides

TL;DR

This paper demonstrates mid-infrared quantum cascade laser frequency combs with engineered multi-section waveguides that manage dispersion, resulting in broad, high-power comb operation with narrow linewidths.

Contribution

The authors introduce a novel waveguide design with multiple sections to control dispersion in QCL frequency combs, enabling improved performance.

Findings

Continuous comb operation over large current range

High output power exceeding 380 mW

Wide optical bandwidth over 55 cm-1

Abstract

We present quantum cascade laser (QCL) frequency comb devices with engineered waveguides for managing the dispersion. The QCL waveguide consists of multiple sections with different waveguide widths. The narrow and wide sections of the waveguide are designed in a way to compensate the group velocity dispersion (GVD) of each other and thereby produce a flat and slightly negative GVD for the QCL. The QCL exhibits continuous comb operation over a large part of the dynamic range of the laser. Strong and narrow-linewidth intermode beatnotes are achieved in more than 300 mA wide operation current range. The comb device features also considerably high output power (>380 mW) and wide optical bandwidth (>55 cm-1)