Fathololoumi S, Dupont E, Razavipour SG, Laframboise SR, Delage A, Wasilewski ZR, Bezinger A, Rafi GZ, Safavi-Naeini S, Ban D, Liu HC. Electrically switching transverse modes in high power THz quantum cascade lasers.
Opt Express 2010;
18:10036-10048. [PMID:
20588857 DOI:
10.1364/oe.18.010036]
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Abstract
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.
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