Terahertz quantum cascade lasers with quasi-periodic resonators

Quasi-periodic surface plasmon gratings based on the Fibonacci sequence are studied as distributed feedback resonators for terahertz quantum cascade lasers. The simulations indicate a quality factor comparable with standard DFB resonators. The fabricated devices show grating-dependent emission, but suppression of higher transverse waveguide modes will be necessary to unambiguously identify the fundamental resonance frequencies of the grating.