Two commercially available large area silicon avalanche photodiodes (APD) were characterized in the laboratory. The response of the APD's to a sequence of 8-bit pulse position modulated (256-PPM) laser pulses, with and without additive background noise, was recorded and stored for post analysis. Empirical probability density functions (pdf's) were constructed from the signal and noise slot data and compared to pdf's predicted by an analytical model based on Webb+Gaussian statistics. The pulse sequence was used to generate bit-error rate (BER) versus signal photons per pulse plots, albeit with large error bars due to the limited number of signal pulses stored. These BER measurements were also compared with analytical results obtained by using the Gaussian and Webb+Gaussian models for APD channel statistics. While the measurements qualitatively reflect features predicted by theory, significant quantitative deviations were displayed between the measurements and theory. The source of these discrepancies is not currently well understood, but it is surmised that inaccurate knowledge of detector parameters such as gain and noise equivalent temperature models may explain the discrepancies.

Date Published: 20 June 2001
PDF: 9 pages
Proc. SPIE 4272, Free-Space Laser Communication Technologies XIII, (20 June 2001);

Published in SPIE Proceedings Vol. 4272:
Free-Space Laser Communication Technologies XIII
G. Stephen Mecherle, Editor(s)