PROCEEDINGS ARTICLE | September 8, 2011
Proc. SPIE. 8193, International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications
KEYWORDS: Infrared detectors, Infrared sensors, Photovoltaics, Continuous wave operation, Mercury cadmium telluride, Sensors, Laser irradiation, Analytical research, Photovoltaic detectors, Pulsed laser operation
In the experiments of photovoltaic detectors illuminated by CW lasers, some new mechanism has been
found, such as power saturation of photovoltage, hot carrier effect, as well as thermovoltage effect. To
investigate whether there is similar mechanism with pulsed laser irradiating, an 808nm femtosecond
pulsed laser is adopted. In the experiments, three photovoltaic infrared detectors are used, namely short
wavelength HgCdTe detector, medium wavelength HgCdTe detector and medium wavelength InSb
detector. Actually, the 808nm pulsed laser is spectral related laser for short wavelength HgCdTe
detector while spectral unrelated laser for medium wavelength HgCdTe and InSb detector. Under
various power densities, the detectors have a series of outputs. Power saturation of photovoltage is
observed. However, the characteristics of the outputs of these three detectors are quite different, even
between medium wavelength HgCdTe and InSb detector, which have the same packing method. There
are three major contributions in the paper. Firstly, explain the mechanism of power saturation of
photovoltage, mainly from hot carrier effect and the depressed ability of PN junction to separate
electrons and holes with the higher temperature induced by the laser. Secondly, compare the differences
between medium wavelength HgCdTe and InSb detector and give a qualitative analysis. Finally, the
difference of the outputs between short and medium wavelength HgCdTe detector is compared and
qualitatively analyzed, too, with the different mechanisms of interaction between infrared detectors and
spectral related or spectral unrelated laser. The experimental results and theory analysis will show
valuable clue for future research on photovoltaic detector irradiated by pulsed laser.
