Octave-spanning THz quantum cascade laser

Abstract

We present a THZ quantum cascade 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 takes place from 1.64 THz to 3.35 THz with optical powers of 3 mW and 84 modes above threshold. For narrow waveguides a collapse of the free-running beatnote to linewidths of 980 Hz, limited by jitter, indicate frequency comb operation on a spectral bandwidth as wide as 624 GHz.