A portable biosensing system using tapered fiber sensors utilizing mode interference

Abstract

Tapered optical fiber sensor (TOFS) devices are attractive as biosensors due to their higher sensitivity, accurate measurement capabilities, and real-time operation. The tapered region allows the evanescent electromagnetic (EM) field to extend outside the fiber to enable the detection of minute changes in the refractive index in close proximity to the tapered region. The sensing is achieved using appropriate functionalized tapered fiber surfaces. In this work, a second generation (2G) automated compact TOFS system developed in our lab is tested, and repeatable and stable signals are obtained proving that this device potentially can serve as a portable bio/chemical sensor in the future. Preliminary simulations, using a FFT based split-step beam propagation method, of optical propagation through a tapered fiber leading to the detected signal as a function of scanning wavelength and its phase shift with cladding refractive index are presented.