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Silver-based surface plasmon waveguide for terahertz quantum cascade lasers

delete2018-02-05
delete27
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OA
AI
Y
Yingjun Han *
L
Lianhe Li
J
Juanjuan Zhu
A
A. Valavanis
J
Joshua R. Freeman
M
Mark C. Rosamond
P
Paul Dean
A
A. G. Davies
E
E. H. Linfield
DOI:10.1364/OE.26.003814delete
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Abstract

Abstract

En 中文
Terahertz-frequency quantum cascade lasers (THz QCLs) based on ridge waveguides incorporating silver waveguide layers have been investigated theoretically and experimentally, and compared with traditional gold-based devices. The threshold gain associated with silver-, gold-and copper-based devices, and the effects of titanium adhesion layers and top contact layers, in both surface-plasmon and double-metal waveguide geometries, have been analysed. Our simulations show that silver-based waveguides yield lower losses for THz QCLs across all practical operating temperatures and frequencies. Experimentally, QCLs with silver-based surface-plasmon waveguides were found to exhibit higher operating temperatures and higher output powers compared to those with identical but gold-based waveguides. Specifically, for a three-well resonant phonon active region with a scaled oscillator strength of 0.43 and doping density of 6 : 83 x 10(15) cm(-3), an increase of 5 K in the maximum operating temperature and 40% increase in the output power were demonstrated. These effects were found to be dependent on the active region design, and greater improvements were observed for QCLs with a larger radiative diagonality. Our results indicate that silver-based waveguide structures could potentially enable THz QCLs to operate at high temperatures. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.
Keywords:
ELECTRICAL-RESISTIVITY
OPTICAL-CONSTANTS
AG
MODE
AU
METALS
COPPER
CU
TI
PD
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Journal

Optics Express cover
Optics Express
IF:
3.3
Papers:
6.1W
Citations:
14.3W

Organization

U
university of leeds
Scholars:
3.5W
Papers: 3.3W
Citations: 45