Quantum cascade lasers with voltage defect of less than one longitudinal optical phonon energy

• Published in: Applied physics letters Vol. 94; no. 25; pp. 251114 - 251114-3
• Main Authors: Escarra, Matthew D., Hoffman, Anthony J., Franz, Kale J., Howard, Scott S., Cendejas, Richard, Wang, Xiaojun, Fan, Jen-Yu, Gmachl, Claire
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 22-06-2009
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3155429

Efficient use of applied voltage in quantum cascade (QC) lasers is a critical factor in achieving high wall-plug efficiency and low compliance voltage. We demonstrate a QC laser emitting at
4.2

μ
m
featuring a low voltage defect and short injector with only four quantum wells. Devices with a voltage defect of 20 meV, well below the energy of the longitudinal optical phonons, and a voltage efficiency of 91%, a record value for QC lasers, are reported for pulsed operation at 180 K. Voltage efficiencies of greater than 80% are exhibited at room temperature. Overall performance showed wall-plug efficiencies ranging from 21% at cryogenic temperatures to 5.3% at room temperature.