Planarized waveguides for high-performance THz quantum cascade laser frequency

Abstract

We present a planarized double metal waveguide THz quantum cascade laser, where the top contact metallization extends beyond the active region, above the surrounding low-loss BCB polymer. Placing wire bonds over the BCB-covered area enables the fabrication of extremely narrow waveguide dimensions with reduced power dissipation. Compared to a standard double metal waveguide, improvements in waveguide losses, dispersion, RF and thermal properties are observed. Measurement results feature frequency comb operation with free-running beatnotes as strong as -30 dBm, self-starting harmonic states, RF-driven broadband emission, comb operation up to 110 K, and laser operation up to 118 K in continuous-wave.