Highly sensitive surface plasmon resonance sensor using perforated optical fiber for biomedical applications

In this paper, a novel mechanism for design of optical fiber refractive index sensors based on surface plasmon resonance (SPR) is suggested. In the proposed method, the internal part of the fiber core is removed to guide the incident light closer to the clad-core interface. Thereafter, the clad is removed and a thin film of gold is coated on the outer part of the core. In the proposed structure, the light beam is guided between the inner and outer parts of the core, where surface plasmons (SPs) are excited. As a result, the absorption reaches to a maximum at SPR wavelengths. The proposed structure is numerically analyzed using finite difference time domain (FDTD) method. The absorption values at the transmitted power spectra correspond to the dielectric constants of the analyte which surrounds the metal. The refractive indices of bio-materials in the range of 1.3 and 1.41 can be measured by the proposed sensor. According to the simulation results, the proposed biosensor has a maximum sensitivity of about 10570 nm/RIU and its average figure of merit is equal to 97.88. The simulation results confirm that the presented structure can be used for bio-sensing applications.