Surface emission from episide-down short distributed-feedback quantum cascade lasers.
Increased coupling is observed in distributed-feedback quantum cascade lasers when placing a shallow second order grating between a continuous surface-plasmon layer and the active region. The combined effect of an air cladding and a metallic layer on the opposite sides of the waveguide increases the overlap with the grating region resulting in calculated coupling coefficients up to 100 cm(-1). The waveguide design was implemented by Au thermo-compression bonding after grating formation and subsequent backside processing of ridges with air claddings. Lasers as short as 176 microm show single-mode behavior with a side-mode-suppression-ratio of 20 dB and thresholds (10 kA/cm(2)) as well as output powers (> 150 mW) close to Fabry-Pérot device performances are reached for 360 microm long devices.
Schartner
Stephan
S
Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria. Stephan.Schartner@tuwien.ac.at
Austerer
Maximilian
M
Schrenk
Werner
W
Andrews
Aaron M
AM
Klang
Pavel
P
Strasser
Gottfried
G
D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D007259:Infrared Rays; D007834:Lasers; D008962:Models, Theoretical; D011789:Quantum Theory; D012031:Refractometry / Q000295:instrumentation*