Open Access
18 March 2024 Fiber bundle-based beam tracking approach for free space optical communications link optimization
Krunal Patel, Michelle O’Toole, Katherine Newell, Radha Venkat, Hala Tomey
Author Affiliations +
Abstract

A robust pointing, acquisition, and tracking approach is critical to closing and maintaining a free space optical communications link. Many fiber-coupled terminal architectures use a beamsplitter to direct a portion of the received light onto a quadrant detector and generate an error signal. A feedback control loop uses this error signal to adjust a fine steering element to maximize power into the collection fiber. However, this approach produces additional insertion loss due to transmission through a beamsplitter and tracking loss due to inevitable boresighting errors between the quadrant detector and the collection fiber. We present an alternative architecture that makes use of a hexagonally packed, seven-fiber bundle for data beam tracking. The outer fibers are inherently co-boresighted position sensors used to sense displacement of the received beam from the central data fiber. We present field test data directly comparing performance between a fiber bundle-based terminal and a quadrant detector-based terminal. Our results show nearly an order of magnitude of improvement in control loop tracking stability and a 2.8× improvement in tracking performance as seen in Strehl ratio for the fiber bundle system.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Krunal Patel, Michelle O’Toole, Katherine Newell, Radha Venkat, and Hala Tomey "Fiber bundle-based beam tracking approach for free space optical communications link optimization," Optical Engineering 63(4), 041212 (18 March 2024). https://doi.org/10.1117/1.OE.63.4.041212
Received: 15 August 2023; Accepted: 24 February 2024; Published: 18 March 2024
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KEYWORDS
Sensors

Free space optics

Receivers

Single mode fibers

Optical tracking

Beam splitters

Position sensors

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