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Quadratic detection with two-photon quantum well infrared photodetectors

: Schneider, H.; Liu, H.C.; Winnerl, S.; Song, C.Y.; Drachenko, O.; Walther, M.; Faist, J.; Helm, M.


Infrared physics and technology 52 (2009), No.6, pp.419-423
ISSN: 1350-4495
International Conference on Quantum Structure Infrared Photodetectors (QSIP) <2009, Yosemite/Calif.>
Journal Article, Conference Paper
Fraunhofer IAF ()
quantum well infrared photodetector; two-photon intersubband transition; quadratic autocorrelation

Two-photon quantum well infrared photodetectors (QWIPs) involving three equidistant subbands take advantage of a resonantly enhanced optical nonlinearity, which is six orders of magnitude stronger than in a bulk semiconductor. This approach results in a sensitive device to measure quadratic autocorrelation of mid-infrared optical pulses from modelocked quantum cascade lasers, nonlinear optical conversion, and free-electron lasers (FEL). We report on autocorrelation measurements at wavelengths in the midinfrared and Terahertz regimes using ps optical pulses from the FEL at the Forschungszentrum Dresden Rossendorf. In particular, quadratic detection at wavelengths around 5.5 lm is still possible at room-temperature, which is crucial for applications in practical systems. We also report on a two-photon detector which works below the Reststrahlen band at 42 lm (7.1 THz).