COMPARISON BETWEEN PROPAGATION CHARACTERISTICS OF SOME PHOTONIC FIBER-BASED PLASMONIC SENSORS

The birefringence characteristics of recently studied photonic fiber based plasmonic sensors are investigated using a finite element method. The fiber is made by a SiO2 core with fourteen small air holes (of radius r) placed at the vertices of a two-ring hexagonal lattice in which two horizontal holes surrounded a smaller central hole (of radius r(1)) are omitted to introduce the birefringence behavior. The radius of two air-holes in the second ring at the same row with the central air-hole is reduced to r/2. This fiber structure supports two types (I and II) of resonant modes. In this sensor there is a stronger interaction between the core and plasmon modes of type II near the phase matching point for the x-component of the electric field as compared to the y-component, in contradiction with recently published results for a similar fiber structure. The advantages of the x-polarization of the core modes of type II are a smaller spectral width and a smaller value of the propagation length due to a large absorption at the resonance wavelength.