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 foc us the light, and to excite effectively the HE11 mode. A focused ion b eam and selective chemical etching were used for fabrication. Over a 1 000-fold increase in the throughput of the triple-tapered probe with t he aperture diameter D<100 nm was realized in comparison with the conv entional single-tapered probe. Furthermore, due to the third taper wit h a small cone angle, the localized optical near field on the triple-t apered apertured probe with D=60 nm has been confirmed. (C) 1998 Ameri can Institute of Physics. [S0003-6951(98)03041-1].