In-plane and surface emitting high performance THz pillar type photonic crystal lasers with complete photonic bandgaps

Photonic crystal (PhC) band engineering has been shown to be a method of choice to control the emitting properties of quantum cascade lasers (QCLs) [1,2] at THz frequency [3-6]. For PhC distribute-feedback (DFB) type lasers, the low group velocity is responsible for a significant gain enhancement, proportional to the group index [7]. The double plasmon waveguide, in which the TM polarized light is confined in the active region between two metallic layers, enables the fabrication of pillar structures possessing multiple complete photonic bandgaps (PBG) with very low intrinsic losses. In this work, we will present and discuss that pillar type PhC provides, along with spectral control of the light, lower losses, broader single mode tuneability and higher operating temperature than a state of the art fabricated FP cavity [3]. Accompanied with these in-plane emitting properties at 3 THz, we will show that the laser emission can be achieved in surface direction at 1.5 THz with PhC band structure engineering.