IV-VI resonant cavity enhanced photodetectors for the midinfrared
  A resonant-cavity enhanced detector operating in the mid-infrared at a wavelength around 3.6 micron is demonstrated. The device is based on a narrow-gap lead salt heterostructure grown by molecular beam epitaxy. Below 140 K, the photovoltage clearly shows a single narrow cavity resonance, with a relative line width of only 2 % at 80 K. 
M. Boeberl, T. Fromherz, T. Schwarzl, G. Springholz and W. Heiss