Asymmetric quantum wells generate intersubband stimulated emission

June 1, 1997
Optical pumping of a GaAs/AlGaAs quantum-well structure with a free-electron laser enabled researchers at the Universitè Paris-Sud (Orsay, France), in collaboration with others in France and the USA, to obtain intersubband stimulated emission at 77 K with a gain of approximately 80 cm-1 at 12.5 µm. The device differs from quantum cascade lasers--it consists of a pair of asymmetric-coupled quantum wells with three conduction-bound levels. The layer thicknesses of the quantum wells control

Asymmetric quantum wells generate intersubband stimulated emission

Optical pumping of a GaAs/AlGaAs quantum-well structure with a free-electron laser enabled researchers at the Universitè Paris-Sud (Orsay, France), in collaboration with others in France and the USA, to obtain intersubband stimulated emission at 77 K with a gain of approximately 80 cm-1 at 12.5 µm. The device differs from quantum cascade lasers--it consists of a pair of asymmetric-coupled quantum wells with three conduction-bound levels. The layer thicknesses of the quantum wells control phonon scattering of electrons between subbands, determining the carrier lifetime in each band to achieve population inversion.

To increase interaction length, the quantum wells were integrated into 0.7- and 2-mm-long IR waveguides grown on n-doped GaAs substrates. The devices consist of a 5-µm-thick AlGaAs cladding layer, a 2.5-µm-thick GaAs core layer, the active region, and a second GaAs core layer, which is 2.9 µm thick. The active region contains 30 periods of coupled quantum wells, 7.7 and 4.7 nm thick, respectively. A 1.1-nm-thick AlGaAs coupling barrier separates the wells, and the periods are separated by a 21-nm-thick AlGaAs barrier. The device was pumped at 9.2 µm from the free-electron laser, and a 12.5-µm probe beam simultaneously monitored the stimulated emission. Waveguide losses were too high for laser oscillation, but the grou¥expects a 5-mm-long device to lase in the near future.

Sponsored Recommendations

SLP feature for lighting control available on cameras offering

Nov. 28, 2023
A proprietary structured light projector (SLP) feature is now available on the company’s camera series, including the ace 2, boost R, ace U, and ace L.

Chroma Customer Spotlight - Dr. David Warshaw, About his Lab

Nov. 27, 2023
David Warshaw, Professor and Chair of Molecular Physiology and Biophysics at the University of Vermont (UVM), walks us through his lab. Learn about his lab’s work with the protein...

Catalog of Filters and Filter Sets

Nov. 27, 2023
This price list provides information about the filter sets Chroma Technology has created for the multitude of fluorochromes that are typically used in epi-fluorescence microscopy...

Handbook of Optical Filters for Fluorescence Microscopy

Nov. 27, 2023
Fluorescence microscopy requires optical filters that have demanding spectral and physical characteristics. These performance requirements can vary greatly depending on the specific...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!