Open AccessElectrically switching transverse modes in high power THz quantum cascade lasers
Author(s) -
Saeed Fathololoumi,
Emmanuel Dupont,
Seyed Ghasem Razavipour,
S. R. Laframboise,
A. Delâge,
Z. R. Wasilewski,
A. Bezinger,
G.Z. Rafi,
Safieddin SafaviNaeini,
Dayan Ban,
H.C. Liu
Publication year - 2010
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.010036
Subject(s) - lasing threshold , optics , terahertz radiation , laser , cascade , transverse mode , physics , transverse plane , beam (structure) , current density , quantum cascade laser , optoelectronics , materials science , chemistry , structural engineering , chromatography , quantum mechanics , engineering
The design and fabrication of a high power THz quantum cascade laser (QCL), with electrically controllable transverse mode is presented. The switching of the beam pattern results in dynamic beam switching using a symmetric side current injection scheme. The angular-resolved L-I curves measurements, near-field and far-field patterns and angular-resolved lasing spectra are presented. The measurement results confirm that the quasi-TM(01) transverse mode lases first and dominates the lasing operation at lower current injection, while the quasi-TM(00) mode lases at a higher threshold current density and becomes dominant at high current injection. The near-field and far-field measurements confirm that the lasing THz beam is maneuvered by 25 degrees in emission angle, when the current density changes from 1.9 kA/cm(2) to 2.3 kA/cm(2). A two-dimension (2D) current and mode calculation provides a simple model to explain the behavior of each mode under different bias conditions.