Title

Experimental Demonstration of Coherent Beam Combining Over A 7 km Propagation Path

Document Type

Article

Publication Date

11-15-2011

Publication Source

Optics Letters

Abstract

We demonstrate coherent combining (phase locking) of seven laser beams emerging from an adaptive fiber- collimator array over a 7km atmospheric propagation path using a target-in-the-loop (TIL) setting. Adaptive control of the piston and the tip and tilt wavefront phase at each fiber-collimator subaperture resulted in automatic focusing of the combined beam onto an unresolved retroreflector target (corner cube) with precompensation of quasi-static and atmospheric turbulence-induced phase aberrations. Both phase locking (piston) and tip–tilt control were performed by maximizing the target-return optical power using iterative stochastic parallel gradient descent (SPGD) techniques. The performance of TIL coherent beam combining and atmospheric mitigation was significantly increased by using an SPGD control variation that accounts for the round-trip propagation delay (delayed SPGD).

Inclusive pages

4455-4457

ISBN/ISSN

0146-9592

Comments

© 2011 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.

Permission documentation is on file.

Publisher

Optical Society of America

Volume

36

Issue

22

Peer Reviewed

yes


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