Title :
Waveguide design for bi-modal operation of THz quantum cascade lasers
Author :
Razavipour, S.G. ; Fathololoumi, S. ; Rafi, G.Z. ; Ban, D. ; Safavi-Naeini, S. ; Laframboise, S.R. ; Wasilewski, Z.R. ; Liu, H.C.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Waterloo, Waterloo, ON, Canada
Abstract :
The design and fabrication of a bi-modal semi-insulating surface-plasmon waveguide for a quantum cascade laser emitting at 3.75 THz is presented. Different transverse modes are excited under different electric current injection due to their different overlapping with the laterally nonuniform gain profile in the active region. HFSS and COMSOL program are used to simulate the near/far field and waveguide loss for various waveguide structures, respectively. It is found that a 150 μm wide surface-plasmon waveguide allows either co-excitation or selective excitation of the first two transverse modes. The total optical loss (i.e., the combination of waveguide and mirror loss) is found below 20 cm-1. An electrically controllable dynamic beam pattern steering is predicted. The near field and far field measurements of a fabricated quantum cascade laser device confirm the theoretical results. The dynamic switching of far-field beam pattern by an angle of 25° is observed when the injected current density changes from 1.9 kA/cm2 to 2.3 kA/cm2.
Keywords :
millimetre wave lasers; optical design techniques; optical fabrication; optical waveguides; quantum cascade lasers; surface plasmons; COMSOL; HFSS; THz quantum cascade lasers; bi-modal operation; bi-modal semi-insulating surface-plasmon waveguide; electric current injection; frequency 3.75 THz; quantum cascade laser device; size 150 mum; transverse modes; waveguide design; waveguide loss; waveguide structures; Laser beams; Laser excitation; Optical design; Optical device fabrication; Optical losses; Optical surface waves; Optical waveguides; Quantum cascade lasers; Surface emitting lasers; Surface waves; Beam steering; dielectric waveguides; submillimeter wave lasers;
Conference_Titel :
Microwave Symposium Digest (MTT), 2010 IEEE MTT-S International
Conference_Location :
Anaheim, CA
Print_ISBN :
978-1-4244-6056-4
Electronic_ISBN :
0149-645X
DOI :
10.1109/MWSYM.2010.5514815