Spectral gain profile of a multi-stack terahertz quantum cascade laser

Journal Article · Mon Nov 03 04:00:00 EST 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4901316· OSTI ID:22391895

Deutsch, C.; Krall, M.; Unterrainer, K.; Darmo, J. ^[1]; Rösch, M.; Scalari, G.; Beck, M.; Faist, J. ^[2]

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1. Photonics Institute, Vienna University of Technology, Gußhausstraße 27-29, 1040 Vienna (Austria)
2. Institute for Quantum Electronics, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich (Switzerland)

The spectral gain of a multi-stack terahertz quantum cascade laser, composed of three active regions with emission frequencies centered at 2.3, 2.7, and 3.0 THz, is studied as a function of driving current and temperature using terahertz time-domain spectroscopy. The optical gain associated with the particular quantum cascade stacks clamps at different driving currents and saturates to different values. We attribute these observations to varying pumping efficiencies of the respective upper laser states and to frequency dependent optical losses. The multi-stack active region exhibits a spectral gain full width at half-maximum of 1.1 THz. Bandwidth and spectral position of the measured gain match with the broadband laser emission. As the laser action ceases with increasing operating temperature, the gain at the dominant lasing frequency of 2.65 THz degrades sharply.

• OSTI ID: 22391895
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 18 Vol. 105; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EFFICIENCY
EMISSION
FREQUENCY DEPENDENCE
LASERS
PUMPING
SPECTROSCOPY
THZ RANGE 01-100