Hollow fiber sensor based on metal-cladding waveguide with extended detection range

A new hollow fiber sensor based on metal-cladding waveguide configuration for the detection of the refractive index of liquid is proposed and demonstrated. Due to the existence of both surface and guided modes in the metal-insulator-metal waveguide, the proposed sensor can detect liquid with refractive index either higher or lower than the insulator layer, which significantly extends the detection range. The characteristics of metalcladding waveguide is analyzed and presented, while the performance of the sensor is numerically calculated and evaluated. The results evince that, the designed fiber sensor can effectively detect both high and low refractive index liquid by respectively exciting surface mode and guided mode. (C) 2017 Optical Society of America