Numerical Analysis of Microstructured Optical Fiber for Applications in SPR Sensing

In recent years, fiber-optic sensor technology has been boosted to industrial and biomedical applications, with the emergence of sensors based on Surface Plasmon Resonance (SPR) phenomenon. During the 1990s, a new technology... [ view full abstract ]

In recent years, fiber-optic sensor technology has been boosted to industrial and biomedical applications, with the emergence of sensors based on Surface Plasmon Resonance (SPR) phenomenon. During the 1990s, a new technology was introduced in the manufacture of optical fibers, where elements called photonic crystals became the raw material used for the construction and characterization of these fibers. This new technology has boosted interest in the study of photonic crystal fibers (PCFs), which consist of microstructured waveguides. The development of optical sensors in microstructured fibers becomes a very attractive alternative for several applications in sensing, and can be used in the monitoring of physical, chemical and biological parameters, relevant to the maintenance of the quality of products in the industry and in biomedical applications with the detection of pathologies through fluids, due to the development and optimization of devices for compact, accurate and low cost laboratory tests in comparison with the existing ones. This work presents the numerical analysis of a biosensor proposal constructed with fibers of photonic crystals of silica, using gold in the sensory region. Numerical characterization considers the Angular Interrogation Mode (AIM) with wavelength set at 800 nm. The numerical analysis was performed with the aid of software based on the finite element method (FEM). Using perfectly coupled layers and boundary conditions for light scattering. The metal layer and the analyte were placed in the outer layer of the D-shaped fiber in order to facilitate detection and practical implementation. This study served to validate the use of these fibers for the construction of SPR sensors. The future prospect is the manufacture of an optical biochip inspired by these fibers, with larger dimensions in order to facilitate manipulation and testing. The best polishing of the fabricated structure will also be defined in order to obtain the surface for deposition of the metal. Figure 1 shows the coupling of light in a solid-core PCF, where the occurrence of SPR in the fiber can be seen.