An intensity curvature sensor using a Photonic Crystal Fiber (PCF) with three coupled cores is proposed. The three cores were aligned and there was an air hole between each two consecutive cores. The fiber had a low air filling fraction, which means that the cores remain coupled in the wavelength region studied. Due to this coupling interference is obtained in the fiber output even if just a single core is illuminated. A configuration using transmission interrogation, which used a section fiber with 0.08 m of PCF as the sensing head, and a configuration using reflection interrogation, which used a section fiber with 0.13 m of PCF as the sensing head, were characterized and compared for curvature sensing. When the fiber is bended along the plane of the cores, one of the lateral cores will be stretched and the other compressed. This changes the coupling between the three cores, changing the optical power intensity. The sensibility of the sensing head was strongly dependent on the direction of bending, having its maximum when the bending direction was along the plane of the cores. A maximum curvature sensitivity of 1.8 dB.m was demonstrated between 0 m and 2.8 m.

Date Published: 25 April 2012
PDF: 8 pages
Proc. SPIE 8426, Microstructured and Specialty Optical Fibres, 84260F (25 April 2012); doi: 10.1117/12.922784

Published in SPIE Proceedings Vol. 8426:
Microstructured and Specialty Optical Fibres
Kyriacos Kalli; Alexis Mendez, Editor(s)