Comprehensive numerical analysis of a surface-plasmon-resonance sensor based on an H-shaped optical fiber.

We present and numerically characterize a surface-plasmon-resonance sensor based on an H-shaped optical fiber. In our design, the two U-shaped grooves of the H-fiber are first coated with a thin gold layer and then covered by a uniform titanium dioxide layer to facilitate spectral tuning of the device. A finite element method analysis of the sensor indicates that a refractive-index resolution of up to 5 · 10(3) nm/RIU can be obtained.

Surface-plasmon-resonance sensor based on three-hole microstructured optical fiber.

We propose a novel surface-plasmon-resonance sensor design based on coating the holes of a three-hole microstructured optical fiber with a low-index dielectric layer on top of which a gold layer is deposited. The use of all three fiber holes and their relatively large size should facilitate the fabrication of the inclusions and the infiltration of the analyte. Our numerical results indicate that the optical loss of the Gaussian guided mode can be made very small by tuning the thickness of the dielectric layer and that the refractive-index resolution for aqueous analytes is 1x 10(-4).

Modal analysis of the self-imaging phenomenon in optical fibers with an annular core.

We investigate the occurrence of self-images, or Talbot images, in a spatially multimode field that propagates along an optical fiber whose core has an annular-shaped cross section. By use of full-vectorial modal analysis, we study the effect of the transverse fiber dimensions on the self-imaging properties. According to our analysis, good self-images can be expected when the fiber core is thin and the modes are far from their cutoffs. However, as the core diameter is made larger to increase the number of modes available in the imaging, the general self-imaging properties tend to deteriorate.

Modal analysis of M-type-dielectric-profile optical fibers in the weakly guiding approximation.

We study the applicability of the weakly guiding approximation (WGA) to the modal analysis of an M-type optical fiber in which a ring-shaped core lies between two uniform cladding layers. Besides being dependent on the refractive indices, the accuracy of the approximation is shown to be substantially affected by the transverse dimensions of the core. The accuracy is characterized by calculating an overlap integral between the exact and WGA-approximated modal fields. Fibers that have an inner cladding similar to the outer cladding, or similar to vacuum, are considered in detail. The feasibility of the WGA in determining the fiber parameters for single-mode guidance is also discussed.