Mid-Infrared Frequency Combs and Pulse Generation based on Single Section Interband Cascade Lasers

TL;DR

This paper demonstrates that single-section Interband Cascade Lasers can generate mid-infrared frequency combs and short pulses, offering a simpler design with potential for high peak power applications.

Contribution

It introduces a novel single long section cavity design for ICLs that enables frequency comb generation and pulse production in the mid-infrared range.

Findings

Achieved frequency combs at ~4.2 μm with narrow beatnotes

Reconstructed ultrafast temporal response using modified SWIFT spectroscopy

Generated ~3 ps pulses through active modelocking

Abstract

Interband Cascade Lasers (ICLs) are semiconductor lasers emitting in the mid-wave infrared (MWIR 3-6 {\mu}m) and can operate as frequency combs (FCs). These demonstrations are based on double section cavities that can reduce dispersion and/or are adapted for radio-frequency operation. Here we show that ICLs FCs at long wavelengths, where the refractive index dispersion reduces, can be realized in a single long section cavity. We show FC generation for ICLs operating at {\lambda} ~ 4.2 {\mu}m, demonstrating narrow electrical beatnotes over a large current range. We also reconstruct the ultrafast temporal response through a modified SWIFT spectroscopy setup with two fast MWIR detectors, which shows a frequency modulated response in free-running operation. Further, we show that, through active modelocking, the ICL can be forced to generate short pulses on the order of 3 ps. This temporal response is in agreement with Maxwell Bloch simulations, highlighting that these devices possess long dynamics (~100ps) and potentially makes them appropriate for the generation of large peak powers in the MWIR.