Summary: IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 42, NO. 3, MARCH 2006 257
Analysis of Terahertz Surface Emitting
Martin Schubert, Student Member, IEEE, and Farhan Rana, Member, IEEE
Abstract--An analysis of surface-emitting terahertz quantum-
cascade lasers operating at wavelengths near 100 m is presented.
The devices use distributed feedback through second-order Bragg
metal gratings to generate strong emission of radiation normal
to the laser surface. The analysis is based on coupling between
the exact FloquetBloch eigenmodes of infinite periodic struc-
tures in finite length devices. The results show performance of
surface-emitting terahertz lasers comparable to edge-emitting
devices, with high radiative efficiencies and low threshold gains.
Using phase-shifts in the grating, high-quality single-lobe beams
in the farfield are obtained.
Index Terms--Coupling coefficients, distributed feedback (DFB)
lasers, FloquetBloch expansion, quantum-cascade laser, surface
TERAHERTZ quantum-cascade lasers are emerging as im-