On the coupling efficiency of metal-coated near-field probes.
A theory for calculating the optical transmission of nanometric circular apertures in a thick and perfectly conducting screen coated upon an optical fibre has been developed. The theory is intended for the study of near-field probes and differs from other well known theories of radiation transmission through subwavelength apertures in the fact that it includes an optical fibre, making possible to distinguish which part of energy passing through the aperture is effectively coupled in guided modes. In a scanning near-field optical microscope tip, only the guided modes will reach the photodetector, and will contribute to the final read-out. A numerical calculation for different fibre parameters, to show the dependence of the guided transmission coefficient for the guided modes of the fibre, is presented. The agreement of the theory with earlier calculations where the optical fibre is not included is emphasized.
Alvarez
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L
Centro de Investigación Científica y Educación Superior de Ensenada, CP 22800, Ensenada, Baja California, México. lydia@ccmc.unam.mx
Xiao
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M