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Proceedings Paper

8-W coherently phased 4-element fiber array
Author(s): Jesse Anderegg; Stephen John Brosnan; Mark E. Weber; Hiroshi Komine; Michael G. Wickham
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Paper Abstract

A four-element fiber array has been constructed to yield 8 watts of coherently phased, linearly polarized light energy in a single far field spot. Each element consists of a 2-W single-mode fiber-amplifier chain. Phase control of each element is achieved with a lithium-niobate phase modulator. A master laser provides a linearly polarized, narrow linewidth signal that is split into five channels. Four channels are individually amplified using polarization maintaining fiber power amplifiers. Frequency broadening of the signal is necessary to avoid stimulated Brillouin scattering. The fifth channel is used as a reference arm. It is frequency shifted and then combined interferometrically with a portion of each channel's signal. Detectors sense the heterodyne modulation signal, and an electronics circuit measures the relative phase for each channel. Compensating adjustments are then made to each channel's phase modulator. The stability of the optical train is an essential contributor to its success. A state-of-the-art interferometer was built with mountless optics. A lens array was constructed using nano-positioning tolerances, where each lens was individually aligned to its respective fiber to collimate its output and point it at a common far field spot. This system proved to be highly robust and handled any acoustic perturbations.

Paper Details

Date Published: 3 July 2003
PDF: 6 pages
Proc. SPIE 4974, Advances in Fiber Lasers, (3 July 2003); doi: 10.1117/12.478311
Show Author Affiliations
Jesse Anderegg, TRW, Inc. (United States)
Stephen John Brosnan, TRW, Inc. (United States)
Mark E. Weber, TRW, Inc. (United States)
Hiroshi Komine, TRW, Inc. (United States)
Michael G. Wickham, TRW, Inc. (United States)


Published in SPIE Proceedings Vol. 4974:
Advances in Fiber Lasers
L. N. Durvasula, Editor(s)

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