1 April 2008 Fiber modal Michelson interferometers with coherence addressing and heterodyne interrogation
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Abstract
A long-period-grating-based fiber optic Michelson modal interferometer with coherence addressing and heterodyne interrogation is studied as a sensing structure for measuring environmental refractive index, temperature, and liquid level. The effects of several system parameters on the measurements are investigated. Experimental results show that the sensitivity to the external refractive index increases with the order of cladding mode and with a reduction of the fiber diameter. The decrease of the fiber diameter from 125 µm down to 70 μm enhances the sensitivity to the external index by a factor of 2.7. It is also shown that the use of a silica-core fiber increases the sensitivity to the external index by a factor of 1.4 and reduces the thermal sensitivity by a factor of 2.5 compared to a standard fiber.
© (2008) Society of Photo-Optical Instrumentation Engineers (SPIE)
Paulo Caldas, Paulo Caldas, Pedro A. S. Jorge, Pedro A. S. Jorge, F. M. Araujo, F. M. Araujo, Luís Alberto Ferreira, Luís Alberto Ferreira, M. B. Marques, M. B. Marques, Gaspar M. Rego, Gaspar M. Rego, José Luís Santos, José Luís Santos, } "Fiber modal Michelson interferometers with coherence addressing and heterodyne interrogation," Optical Engineering 47(4), 044401 (1 April 2008). https://doi.org/10.1117/1.2903089 . Submission:
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