RESUMEN
We analyze two basic aspects of a scanning near-field optical microscope (SNOM) probe's operation: (i) spot-size evolution of the electric field along the probe with and without a metal layer, and (ii) a modal analysis of the SNOM probe, particularly in close proximity to the aperture. A slab waveguide model is utilized to minimize the analytical complexity, yet provides useful quantitative results--including losses associated with the metal coating--which can then be used as design rules.
Asunto(s)
Diseño Asistido por Computadora , Análisis de Falla de Equipo , Microscopía de Fuerza Atómica/instrumentación , Microscopía Confocal/instrumentación , Transductores , Galvanoplastia , Diseño de Equipo , Calor , Microscopía de Fuerza Atómica/métodos , Microscopía Confocal/métodos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
A combination of controlled annealing and characterization by scanning probe microscopy (SPM) is used to demonstrate that the refractive-index proffle of a commercially available silica-based optical fiber can be accurately reconfigured for use as an evanescent field sensor. The process relies on the controlled relocation of the silica glass dopants across the fiber cross section through heat treatment and the accurate measurement of the resulting dopant redistribution with SPM and differential etching techniques. The effect of variable annealing along a length of fiber is to produce a mode transformer to couple light from a laser source into the sensing region of the fiber.
