Length Effects of Hetero-Core Optical Biosensor based on Evanescent Field Absorption

Shim, Joon-Hwon; Chan, Joo-Kwang; Sohn, Kyung-Rak

Journal of Navigation and Port Research 2008;32(9):723-727.
Published online December 20, 2008.

Length Effects of Hetero-Core Optical Biosensor based on Evanescent Field Absorption

Joon-Hwon Shim, Joo-Kwang Chan, Kyung-Rak Sohn

Abstract

Sensing perpormances of evanescent field absorption (EFA) hetero-core fiber sensor has been presented based on EFA by changing the length and the core diameter of the single mode fiber. Experimental results have demonstrated a good feature in their relationship between the length and the core diameter of the single mode fiber. The sensor consists of 2 fiber optics which have the same cladding diameter of 125 um However one fiber optic used is single mode and has varying core diameter ranging from 3.3 to 5.6 um The other fiber is multimode type and has a thicker fixed core diameter of 62.5 um The 2 fiber optics are thermally spliced together. Experiments conducted to measure the resonance wavelength were carried out over a range of refractive index, to find the optimum sensing length. Experiments show that core diameter of the single mode fiber and sensing length affects the linearity and sensitivity.

Key Words: evanescent field absorption;hetero-core structure;resonance wavelength;biosensor; optical fiber sensor