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Proceedings Paper • Open Access

Design challenges of a tunable laser interrogator for geo-stationary communication satellites
Author(s): Selwan K. Ibrahim; Arthur Honniball; Raymond McCue; Michael Todd; John A. O’Dowd; David Sheils; Liberis Voudouris; Martin Farnan; Andreas Hurni; Philipp Putzer; Norbert Lemke; Markus Roner

Paper Abstract

Recently optical sensing solutions based on fiber Bragg grating (FBG) technology have been proposed for temperature monitoring in telecommunication satellite platforms with an operational life time beyond 15 years in geo-stationary orbit. Developing radiation hardened optical interrogators designed to be used with FBG sensors inscribed in radiation tolerant fibers offer the capabilities of multiplexing multiple sensors on the same fiber and reducing the overall weight by removing the copper wiring harnesses associated with electrical sensors.

Here we propose the use of a tunable laser based optical interrogator that uses a semiconductor MG-Y type laser that has no moving parts and sweeps across the C-band wavelength range providing optical power to FBG sensors and optical wavelength references such as athermal Etalons and Gas Cells to guarantee stable operation of the interrogator over its targeted life time in radiation exposed environments. The MG-Y laser was calibrated so it remains in a stable operation mode which ensures that no mode hops occur due to aging of the laser, and/or thermal or radiation effects.

The key optical components including tunable laser, references and FBGs were tested for radiation tolerances by emulating the conditions on a geo-stationary satellite including a Total Ionizing Dose (TID) radiation level of up to 100 krad for interrogator components and 25 Mrad for FBGs.

Different tunable laser control, and signal processing algorithms have been designed and developed to fit within specific available radiation hardened FPGAs to guarantee operation of a single interrogator module providing at least 1 sample per second measurement capability across <20 sensors connected to two separate optical channels.

In order to achieve the required temperature specifications of ±0.5°C across a temperature range of -20°C to +65°C using femtosecond inscribed FBGs (fs-FBG), a polarization switch is used to mitigate for the polarization dependent frequency shift (PDFS) induced from fs-FBG which could be in the order of < 20 pm causing < 2°C error in the measurement. Also special transducers were designed to isolate the strain from the FBGs to reduce any strain influence on the FBG temperature measurements while ensuring high thermal conductivity.

In this paper we demonstrate the operation of an optical FBG interrogator as part of a hybrid sensor bus (HSB) engineering model system developed in the frame of an ESA-ARTES program and is planned to be deployed as a flight demonstrator on-board the German Heinrich Hertz geo-stationary satellite.

Paper Details

Date Published: 25 September 2017
PDF: 9 pages
Proc. SPIE 10562, International Conference on Space Optics — ICSO 2016, 105620Y (25 September 2017); doi: 10.1117/12.2296150
Show Author Affiliations
Selwan K. Ibrahim, FAZ Technology Ltd. (Ireland)
Arthur Honniball, FAZ Technology Ltd. (Ireland)
Raymond McCue, FAZ Technology Ltd. (Ireland)
Michael Todd, FAZ Technology Ltd. (Ireland)
John A. O’Dowd, FAZ Technology Ltd. (Ireland)
David Sheils, FAZ Technology Ltd. (Ireland)
Liberis Voudouris, FAZ Technology Ltd. (Ireland)
Martin Farnan, FAZ Technology Ltd. (Ireland)
Andreas Hurni, OHB-System AG (Germany)
Philipp Putzer, OHB-System AG (Germany)
Norbert Lemke, OHB-System AG (Germany)
Markus Roner, OHB-System AG (Germany)

Published in SPIE Proceedings Vol. 10562:
International Conference on Space Optics — ICSO 2016
Bruno Cugny; Nikos Karafolas; Zoran Sodnik, Editor(s)

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