Multimode interference-based fiber sensor in a cavity ring-down system for refractive index measurement

• Type: Article in International Scientific Journal
• Date: 2017

Authors

Susana Silva (Author) FCUP; Frazao, O (Author) FCUP

Journal

Title: Optics and Laser Technology

Vol. 91

Pages: 112-115

ISSN: 0030-3992

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 12 Citations

Other information

Authenticus ID: P-00M-FPD

DOI: 10.1016/j.optlastec.2016.12.029

Abstract (EN): This work reports a multimode interference-based fiber sensor in a cavity ring-down system (CRD) for sensing temperature-induced refractive index (RI) changes of water. The sensing head is based in multimodal interference (MMI) and it is placed inside the fiber loop cavity of the CRD system. A modulated laser source was used to send pulses down into the fiber loop cavity and an erbium-doped fiber amplifier (EDFA) was placed in the fiber ring to provide an observable signal with a reasonable decay time. The behavior of the sensing head to temperature was studied due to its intrinsic sensitivity to said parameter - a sensitivity of -1.6x10(-9) mu s/degrees C was attained. This allowed eliminating the temperature component from RI measurement of water and a linear sensitivity of 580 mu s/RIU in the RI range of 1.324-1.331 was obtained. The use of a MMI fiber sensor in the proposed CRD configuration allowed achieving a sensitivity similar to 4-fold than that obtained with a tilted fiber Bragg grating and similar to 2-fold than that when a micrometric channel inscribed in the fiber was used.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 4