Title :
Multiplexed optical fiber sensors using a single Fabry-Perot resonator for phase modulation
Author :
Chang, Chia-Chen ; Sirkis, Jim
Author_Institution :
Smart Mater. & Structures Res. Center, Maryland Univ., College Park, MD, USA
fDate :
7/1/1996 12:00:00 AM
Abstract :
This paper describes the use of different optical return paths in a single Fabry-Perot phase modulator to perform coherence division multiplexing, and a combination of coherence and frequency division multiplexing of Fabry-Perot interferometric optical fiber sensors. A path-matched differential interferometry (PMDI) using low finesse Fabry-Perot sensors, one moderate finesse Fabry-Perot read-out resonator, and a broadband light source consisting of amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA) is used to illustrate the idea. The first, second and third order of multiple paths in a single Fabry-Perot read-out resonator are used to path-match three Fabry-Perot sensors. These three orders of path-matches provide a single, double and triple depth of modulation (phase-change) when the read-out is used as an optical phase modulator, and therefore provide a single, double and triple carrier frequency when serrodyne demodulation is used. The use of a single moderate finesse read-out Fabry-Perot resonator to simultaneously path-match coherence multiplexed sensors reduces the complexity of the optical system. Experiments and modeling are used to show the existence of the first, second, and third order of interference path-match conditions, and to determine the read-out configuration that enhances the visibility of the higher order path-match conditions. Using the multiple return paths in a single PZT-based Fabry-Perot read-out interferometer and serrodyne demodulation, several multiplexing schemes are investigated, and their relative merits discussed
Keywords :
Fabry-Perot interferometers; Fabry-Perot resonators; demodulation; fibre optic sensors; frequency division multiplexing; optical modulation; phase modulation; superradiance; Fabry-Perot interferometric optical fiber sensors; PZT-based Fabry-Perot read-out interferometer; amplified spontaneous emission; broadband light source; coherence division multiplexing; erbium-doped fiber amplifier; frequency division multiplexing; low finesse Fabry-Perot sensors; moderate finesse Fabry-Perot read-out resonator; moderate finesse read-out Fabry-Perot resonator; multiplexed optical fiber sensors; optical phase modulator; optical return paths; path-matched differential interferometry; phase modulation; serrodyne demodulation; single Fabry-Perot resonator; Coherence; Erbium-doped fiber amplifier; Fabry-Perot; Frequency division multiplexing; Optical fiber sensors; Optical interferometry; Optical modulation; Optical resonators; Optical sensors; Phase modulation;
Journal_Title :
Lightwave Technology, Journal of