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Proceedings Paper

Performance limits of high-rate space-to-ground optical communications through the turbulent atmospheric channel
Author(s): John E. Kaufmann
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Paper Abstract

Atmospheric turbulence corrupts both the amplitude and phase of an optical field propagating from space to an earth-based receiver. While aperture averaging can mitigate amplitude scintillation effects, the performance of single spatial-mode receiver systems such as coherent detection or preamplified direction detection can be significantly degraded by the corrupted phase when the ratio of aperture diameter D to atmospheric coherence length r0 exceeds unity. Although adaptive optics may be employed to correct the wavefront, in practice the correction is imperfect and the residual phase errors induce a communications performance loss. That loss is quantified here by Monte Carlo simulation techniques. Single-mode-receiver fade statistics for imperfect phase correction are calculated in terms of the atmospheric Greenwood frequency fg, the adaptive optic servo loop cutoff frequency fc, and the ratio D/r0. From these statistics, link bit-error rate (BER) performance is calculated. The results reveal that conventional performance measures such as Strehl ratio or mean signal-to- noise ratio loss can significantly underestimate receiver BER losses. Only when the ratio fg/fc is 0.1 or less will communications losses be small (about 0.5 dB) over a wide range of D/r0.

Paper Details

Date Published: 20 April 1995
PDF: 12 pages
Proc. SPIE 2381, Free-Space Laser Communication Technologies VII, (20 April 1995); doi: 10.1117/12.207402
Show Author Affiliations
John E. Kaufmann, MIT Lincoln Lab. (United States)


Published in SPIE Proceedings Vol. 2381:
Free-Space Laser Communication Technologies VII
G. Stephen Mecherle, Editor(s)

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