Phase modulation to intensity modulation conversion for sensitive FBG sensor interrogation

Javier Hervás; David Barrera; Javier Madrigal; Salvador Sales

doi:10.1117/12.2265400

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23 April 2017 Phase modulation to intensity modulation conversion for sensitive FBG sensor interrogation

Javier Hervás, David Barrera, Javier Madrigal, Salvador Sales

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Proceedings Volume 10323, 25th International Conference on Optical Fiber Sensors; 1032342 (2017) https://doi.org/10.1117/12.2265400
Event: 25th International Conference on Optical Fiber Sensors, 2017, Jeju, Korea, Republic of

Abstract

An interrogation technique based on phase modulation to intensity modulation conversion due to FBG filtering is presented. A 10 GHz tone is used to phase modulate an optical carrier located at the Bragg wavelength of a given FBG. The modulation index is set to a small value to keep Bessel identities close to 0 in order to avoid higher harmonics. Changes of the Bragg wavelength cause a power change in the photodetected 10 GHz tone. A remarkable linear sensitivity of 1 dB/pm for a shift up to 10 pm of the Bragg wavelength is demonstrated through experimental measurements. The range with linear sensitivity can be enlarged sweeping the source wavelength. This proves that the presented interrogation technique is able to interrogate FBGs with a resolution far below 1 pm and no need of extra postprocessing.

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Javier Hervás, David Barrera, Javier Madrigal, and Salvador Sales "Phase modulation to intensity modulation conversion for sensitive FBG sensor interrogation", Proc. SPIE 10323, 25th International Conference on Optical Fiber Sensors, 1032342 (23 April 2017); https://doi.org/10.1117/12.2265400

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