Increasing throughput of a near-field optical fiber probe over 1000 times by the use of a triple-tapered structure

We fabricated a new probe with extremely high throughput introducing a triple-tapered structure to reduce the loss in a tapered core, to focus the light, and to excite effectively the HE11 mode. A focused ion beam and selective chemical etching were used for fabrication. Over a 1000-fold increase in the throughput of the triple-tapered probe with the aperture diameter D<100 nm was realized in comparison with the conventional single-tapered probe. Furthermore, due to the third taper with a small cone angle, the localized optical near field on the triple-tapered apertured probe with D=60 nm has been confirmed. (C) 1998 American Institute of Physics. [S0003-6951(98)03041-1].