Adaptive Array of Phase-Locked Fiber Collimators: Analysis and Experimental Demonstration

• Published in: IEEE journal of selected topics in quantum electronics Vol. 15; no. 2; pp. 269 - 280
• Main Authors: Vorontsov, M.A., Weyrauch, T., Beresnev, L.A., Carhart, G.W., Ling Liu, Aschenbach, K.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-03-2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aberration; Adaptive arrays; Adaptive control; Adaptive optics (AO); Adaptive systems; Arrays; Collimators; Compensation; Control systems; Displacement control; Dynamical systems; Fibers; Laboratories; optical arrays; optical beams; Phase shifters; Phased arrays; Pistons; Programmable control
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2008.2010875

We discuss development and integration of a coherent fiber array system composed of densely packed fiber collimators with built-in capabilities for adaptive wavefront phase piston and tilt control at each fiber collimator. In this system, multi-channel fiber-integrated phase shifters are used for phase locking of seven fiber collimators and the precompensation of laboratory-generated turbulence-induced phase aberrations. Controllable x and y displacements of the fiber tips in the fiber collimator array provide additional adaptive compensation of the tip and tilt phase aberration components. An additional control system is utilized for equalization of the intensity of each of the fiber collimator beams. All three control systems are based on the stochastic parallel gradient descent optimization technique. The paper presents the first experimental results of adaptive dynamic phase distortion compensation with an adaptive phase-locked fiber collimator array system.