Ultrasensitive femtosecond two-photon detector with resonantly enhanced nonlinear absorption.
We report on two-photon detection based on nonlinear absorption between subbands in quantum wells. Resonantly enhanced nonlinear absorption, 6 orders of magnitude higher than that of typical bulk semiconductors, leads to a threshold power density for quadratic detection as low as 0.1 W/cm2 and to femtosecond time resolution. The approach facilitates dynamic characterization of the optical light field of infrared emitters with unprecedented sensitivity. We also present a new method for determining the intersubband and intrasubband scattering times by means of autocorrelation measurements.
Schneider
Harald
H
Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastrasse 21, D-79108 Freiburg, Germany. harald.schneider@iaf.fhg.de
Maier
Thomas
T
Liu
H C
HC
Walther
Martin
M
Koidl
Peter
P