Enhanced responsivity with skew ray excitation of reflection- and transmission-type refractometric sensors

The responsivity of optical fibers to refractive index can be enhanced using high-order skew rays compared with using meridional rays. Skew rays can have a much higher number of reflections with increased interaction length along the core-cladding interface, which gives rise to stronger interactions with the external medium. Reflection/transmission-type refractometric sensors based on twin-coupled-core and multimode fibers showed one/two orders of magnitude increase in responsivity with skew ray excitation. The responsivity and sensitivity for the two types are similar to 2000%/RIU, similar to 1400%/RIU, and 4.9 x 10(-5) RIU, 7.0 x 10(-5) RIU, respectively. (C) 2014 Optical Society of America