Letter abstract


Nature Physics 3, 329 - 333 (2007)
Published online: 1 April 2007 | doi:10.1038/nphys577

Subject Categories: Electronics, photonics and device physics | Optical physics

Bloch gain in quantum cascade lasers

Romain Terazzi1,3, Tobias Gresch1,3, Marcella Giovannini1, Nicolas Hoyler1, Norihiko Sekine2 & Jérôme Faist1

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Esaki and Tsu's superlattice1, made by alternating two different semiconductor materials, was the first one-dimensional artificial crystal that demonstrated the ability to tailor semiconductor properties. One motivation of this work was the realization of the Bloch oscillator2, 3 and the use of its particular dispersive optical gain4, 5 to achieve a tuneable source of electromagnetic radiation. However, these superlattices were electrically unstable in the steady state6. Fortunately, because it is based on scattering-assisted transitions, this particular gain does not arise only in superlattices, but also more generally in semiconductor heterostructures7, 8 such as quantum cascade lasers9 (QCLs), where the electrical stability can be controlled10. Here, we show the unambiguous spectral signature of Bloch gain in a special QCL designed to enhance the latter by exhibiting laser action in the condition of weak to vanishing population inversion.

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  1. Institute of Physics, University of Neuchâtel, A.-L. Breguet 1, 2000 Neuchâtel, Switzerland
  2. Institute of Industrial Science, University of Tokyo, 4-6-1 Meguro-ku, Komaba, Tokyo 153-8505, Japan
  3. These authors contributed equally to this work

Correspondence to: Romain Terazzi1,3 e-mail: romain.terazzi@unine.ch

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