Dynamically changing turbulence in the atmosphere distorts the wavefront of the laser beam propagating through it. The resulting spatial and temporal fields of the refractive index lead to performance degradation in the form of reduced signal power and increased BER, even for short link ranges. An electrically addressed liquid crystal spatial light modulator (SLM) can be used to correct the optical path difference (OPD) pattern resulting from the atmospheric distortions. Approximating the phase profile of the distorted beam using well-known Zernike formalism reduces the complexity of controlling each pixel of the SLM. Real time correction of the wavefront can be achieved using the Simplex optimization procedure by Nelder and Mead. Previously, some modifications have been proposed to overcome the local minima problems as well as the faster convergence. Yet the better and faster performance could be achieved by more accurate prediction of the simplex initialization along with the modifications in the simplex procedure. This paper presents the experimental results of such modifications to the earlier proposed system.

Date Published: 13 February 2007
PDF: 8 pages
Proc. SPIE 6457, Free-Space Laser Communication Technologies XIX and Atmospheric Propagation of Electromagnetic Waves, 64570E (13 February 2007); doi: 10.1117/12.708525

Published in SPIE Proceedings Vol. 6457:
Free-Space Laser Communication Technologies XIX and Atmospheric Propagation of Electromagnetic Waves
Steve Mecherle; Olga Korotkova, Editor(s)