New spatial optical filters for gas refractometry

Susana Silva; L. Coelho; R. M. André; O. Frazão

doi:10.1117/12.974991

17 October 2012 New spatial optical filters for gas refractometry

Susana Silva, L. Coelho, R. M. André, O. Frazão

Proceedings Volume 8421, OFS2012 22nd International Conference on Optical Fiber Sensors; 842137 (2012) https://doi.org/10.1117/12.974991
Event: OFS2012 22nd International Conference on Optical Fiber Sensor, 2012, Beijing, China

Abstract

A spatial optical filter based on splice misalignment between optical fibers with different cladding dimensions is proposed for gas refractometry. The sensing head is formed by a 2 mm-long optical fiber with 50 μm diameter spliced with a strong misalignment between two single mode fibers (SMF28) and interrogated in transmission. This fiber structure causes a Fabry-Pérot-behavior along the reduced-size fiber giving at its output end a well defined spatial filtering selectivity. Depending on the misalignment position of the lead-out SMF28, it is possible to obtain two different spectral responses, namely, bandpass or band-rejection filters. It is shown that this filter device is highly sensitive to refractive index changes on a nitrogen (N₂) environment by means of the gas pressure variation. A maximum sensitivity of -1390 nm/RIU for the bandpass filter was achieved.

Citation Download Citation

Susana Silva, L. Coelho, R. M. André, and O. Frazão "New spatial optical filters for gas refractometry", Proc. SPIE 8421, OFS2012 22nd International Conference on Optical Fiber Sensors, 842137 (17 October 2012); https://doi.org/10.1117/12.974991

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