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Enhancing throughput over 100 times by a triple-tapered structure for a near-field optical fiber probe

We have successfully fabricated an extremely high throughput probe for near-field optics 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 100 times 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 probe with D equals 60 nm has been confirmed.