Short-wavelength infrared tuneable filters on HgCdTe photoconductors

The design, micro-fabrication, and electronic and optical performance of a tuneable short-wavelength infrared Fabry-Perot micro-resonator on a mercury cadmium telluride photoconductor is presented. The maximum processing temperature of 125 degrees C has negligible effect on the electronic and optical performance of photoconductor test structures. Maximum responsivity, effective carrier lifetime and detectivity are 60 x 10(3) VW-1, 2 x 10(-5) s and 8 x 10(10) cmHz(1/2)W(-1), respectively. The maximum effective carrier lifetime and specific detectivity are in good agreement with the theoretical maxima. Uncooled device operation is possible since responsivity is observed not to improve with thermo-electric cooling. Spectral tuning of the micro-filters is demonstrated over the wavelength range 1.7 to 2.2 mu m using drive voltages up to 8 V, with the full-width-half-maximum of the resonance approximately 100 nm. Membrane deflection can be up to 40% of the cavity width. (c) 2005 Optical Society of America.