Open AccessThe output power and beam divergence behaviors of tapered terahertz quantum cascade lasers
Author(s) -
Yanfang Li,
Jian Wang,
Ning Yang,
Junqi Liu,
Tao Wang,
Fengqi Liu,
Zhanguo Wang,
Weidong Chu,
Suqing Duan
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.015998
Subject(s) - optics , beam divergence , cascade , laser , terahertz radiation , beam (structure) , materials science , waveguide , laser beam quality , power (physics) , beam diameter , physics , optoelectronics , laser beams , quantum mechanics , chemistry , chromatography
We report on Terahertz quantum cascade lasers with tapered waveguide structure operating at ≈ 103 μm. The tapered waveguide effect on the output power and the laser beam divergence are experimentally studied with the tapered angle ranging from 0° to 8°. It is found that the peak output power of the devices with same length reaches the maximum at about 5° ≈ 6° tapered angle. Meanwhile, the horizontal divergence angle of the laser beam can be greatly reduced. The existence of such optimal tapered angle is explained by the finite-element simulation with the consideration of the self-focusing effect for the devices with larger tapered angle.