Properties of indium antimonide detectors for use as transfer standards for detector calibrations

The properties of 4-mm-diameter and 7-mm-diameter liquid-nitrogen-cooled indium antimonide detectors were investigated to determine their suitability as transfer standards (i.e., reference detectors) for the detector calibration facility at the National Research Council of Canada. The spectral responsivity of the InSb detectors in the spectral range 1000-3000 nm was determined by a two-step procedure involving the use of germanium transfer standards and suitably characterized thermopiles. It is shown that the long-term reproducibility of the InSb detector calibrations is approximately +/-1%. The uniformity and linearity as a function of wavelength, as well as the background current noise and drift of the two detectors, are compared. It is shown that the 7-mm-diameter detector is clearly superior to the 4-mm one for use as a transfer standard. It is estimated that the overall accuracy of the calibrations of the two InSb detectors is +/-2% in the range 1200-2800 nm. (C) 1998 Optical Society of America.