Octave-spanning semiconductor laser

TL;DR

This paper introduces a continuous wave semiconductor laser with an octave-spanning emission in the THz range, featuring homogeneous mode power distribution and potential for THz frequency comb applications.

Contribution

It demonstrates a novel heterogenous quantum cascade laser achieving octave-spanning THz emission with stable frequency comb operation in a continuous wave regime.

Findings

Operates from 1.64 THz to 3.35 THz with mW power levels

Supports over 80 lasing modes above threshold

Achieves a 624 GHz wide frequency comb bandwidth

Abstract

We present here a semiconductor injection laser operating in continuous wave with an emission covering more than one octave in frequency, and displaying homogeneous power distribution among the lasing modes. The gain medium is based on a heterogeneous quantum cascade structure operating in the THz range. Laser emission in continuous wave takes place from 1.64 THz to 3.35 THz with optical powers in the mW range and more than 80 modes above threshold. Free-running beatnote investigations on narrow waveguides with linewidths of 980 Hz limited by jitter indicate frequency comb operation on a spectral bandwidth as wide as 624 GHz, making such devices ideal candidates for octave-spanning semiconductor-laser-based THz frequency combs.