High-performance, ultra-broadband room-temperature terahertz quantum cascade laser sources

We present ultra-broadband room temperature monolithic terahertz quantum cascade laser (QCL) sources based on intra-cavity difference frequency generation, emitting continuously more than one octave in frequency between 1.6 and 3.8 THz, with a peak output power of ~0.2 mW. Broadband terahertz emission is realized by nonlinear mixing between single mode and multi mode spectra due to distributed feedback grating and Fabry-Perot cavity, respectively, in mid-infrared QCLs with a dual-upper-state active region design. Besides, a device showing narrower THz spectrum around ~3 THz provides a peak power of ~0.3 mW and displays a mid-infrared-to-terahertz conversion efficiency of ~1.2 mW/W
²
at room temperature.