Title

Local phase control for a planar array of fiber laser amplifiers

Author Info

Patrick Steffanic, California Polytechnic State University - San Luis Obispo
Benjamin T. Johannes, California Polytechnic State University - San Luis Obispo
Claudia A. Sison, California Polytechnic State University - San Luis Obispo
Gary Hughes, California Polytechnic State University - San Luis ObispoFollow
Philip Lubin, University of California - Santa Barbara
Peter Meinhold, University of California - Santa Barbara
Johnathan Suen, University of California - Santa Barbara
Hugh O'Neill, Ventura College
Miikka Kangas, University of California - Santa Barbara
Travis Brashears, University of California - Santa Barbara
Qicheng Zhang, University of California - Santa Barbara
Janelle Griswold, University of California - Santa Barbara
Jordan Riley, University of California - Santa Barbara
Caio Motta, University of California - Santa Barbara

Recommended Citation

Published in Proceedings of SPIE: San Diego, CA, Volume 9616, August 9, 2015, pages 1-12.

The definitive version is available at https://doi.org/10.1117/12.2189821.

Abstract

Arrays of phase-locked lasers have been developed for numerous directed-energy applications. Phased-array designs are capable of producing higher beam intensity than similar sized multi-beam emitters, and also allow beam steering and beam profile manipulation. In phased-array designs, individual emitter phases must be controllable, based on suitable feedback. Most current control schemes sample individual emitter phases, such as with an array-wide beam splitter, and compare to a master phase reference. Reliance on a global beam splitter limits scalability to larger array sizes due to lack of design modularity. This paper describes a conceptual design and control scheme that relies only on feedback from the array structure itself. A modular and scalable geometry is based on individual hexagonal frames for each emitter; each frame cell consists of a conventional lens mounted in front of the fiber tip. A rigid phase tap structure physically connects two adjacent emitter frame cells. A target sensor is mounted on top of the phase tap, representing the local alignment datum. Optical sensors measure the relative position of the phase tap and target sensor. The tap senses the exit phase of both emitters relative to the target normal plane, providing information to the phase controller for each emitter. As elements are added to the array, relative local position data between adjacent phase taps allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. The approach is scalable for target distance and number of emitters without loss of control.

Disciplines

Statistics and Probability

Copyright

2015 Society of Photo-Optical Instrumentation Engineers

Number of Pages

12

Publisher statement

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 modification of the content of the paper are prohibited.