Opt Express. 2015 Jul 13;23(14):18401-14. doi: 10.1364/OE.23.018401.

Grating enhanced apertureless near-field optical microscopy.

Optics express

Josip Mihaljevic, Christian Hafner, Alfred J Meixner

PMID: 26191898 DOI: 10.1364/OE.23.018401

Abstract

We examine the possibility of optimizing the emission and the near-field signal of apertureless silver and gold tips by using an optimized non-periodic grating. In this context, we consider the emission of a single quantum emitter in close proximity to optimized tips. Additionally, we study the far-field coupling efficiency of a tightly focused beam to the near-field of the tip. The gain in performance is compared with unstructured tips and the comparison with a pure plasmonic excitation of an unstructured tip is discussed. The optimized, structured tips show a significant enhancement of the total decay rate, as a result of standing plasmonic waves between the grating and the tip apex, leading to a resonant behavior. The resonances can be explained well with a Fabry-Pérot model. Furthermore, the total decay rate of an emitter near a structured tip can also be decreased as compared to an unstructured tip, when the grating is shifted from the optimal resonant position. The proposed scheme represents an interesting novel nano-antenna, for which the resonance as well as the directivity can be controlled by the grating.

Publication Types

• Journal Article