THz Quantum Cascade Laser Frequency Combs based on Planarized Waveguides

Abstract

We present a planarized double metal waveguide platform for THz quantum cascade laser frequency combs with a wide top metallization, extending above the surrounding low-loss BCB polymer. Compared to a standard double metal waveguide, improvements in waveguide losses, RF and thermal properties are observed. Tapered waveguide devices display a field-enhancing effect, improving comb performance due to the enhanced four wave mixing process. These devices feature strong free-running beatnotes up to nearly -30 dBm and comb operation at high temperatures up to 115 K in continuous wave.