Title: Study and realisation of an original silicon-germanium light trap detector for large band radiometric measurements

Authors: Z. Ben Achour; S. Abbane; O. Touayar; G. Bonnier

Addresses: Laboratory of Materials, Measurements and Applications, Centre Urbain Nord, University of Carthage, INSAT, 1080 Charguia Cedex, Tunisia ' Laboratory of Materials, Measurements and Applications, Centre Urbain Nord, University of Carthage, INSAT, 1080 Charguia Cedex, Tunisia ' Laboratory of Materials, Measurements and Applications, Centre Urbain Nord, University of Carthage, INSAT, 1080 Charguia Cedex, Tunisia ' Past Head of the Radiometry and Photometry Team of the Institut National de Métrologie (France), 292 Rue Saint Martin, 75 141 Paris cedex 03, France

Abstract: An original accuracy light-trap photodetector has been developed at the "Materials, Measurements and Applications laboratory" of INSAT to serve as a transfer standard detector for optical power measurements in the spectral range from 400 nm to 1600 nm. This detector is a silicon and germanium photodiode-based device and consists of, respectively, two silicon (Hamamatsu) and two germanium (UDT) photodiodes in a light-trapping arrangement. The average reflection coefficient of our detector in the studied spectral range is equal to 0.0020 with a standard deviation of ∼4 × 10⁻⁴ (at 1σ level). The obtained average linearity coefficient over a wide dynamic range is equal to 1.001. This factor is acceptable compared with the uncertainty (about 1.1 × 10⁻³). The realised trap detector offers an average responsivity increase equal to almost two compared with the individual photodiodes. This trap detector was calibrated compared with, respectively, silicon and germanium photodiodes standards and provides a convenient standard with a relative standard uncertainty of 1.5 × 10⁻³ and 2.3 × 10⁻³ for, respectively, silicon and germanium photodiodes (at the 1σ level). This higher uncertainty is mainly due to standard photodiodes uncertainties, to the laser beam quality and to its power stability. In fact, the last two factors were not good enough in our case.

Keywords: light trap detectors; calibration; silicon photodiodes; germanium photodiodes; reflection coefficient; linearity; standard uncertainty; metrology; large band radiometric measurements; optical power measurements.

DOI: 10.1504/IJNT.2015.068891

International Journal of Nanotechnology, 2015 Vol.12 No.8/9, pp.708 - 722

Published online: 17 Apr 2015 *

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