Active photonic crystal terahertz laser operating in upper bands

A series of devices with different filling factors and PhC periods is presented, leading to lasing in the first and second PhC band. The lasers are based on so-called active photonic crystal (PhCs) i.e. the pillars are fabricated from an active THz quantum-cascade layer sequence. Thereby, the pillars themselves produce the required optical feedback and gain. There are no defects incorporated in the PhC, the devices rely on band edge states. For the vertical confinement a double-metal waveguide is used.