Plasmonic antennas as design elements for coherent ultrafast nanophotonics

Daan Brinks; Marta Castro-Lopez; Richard Hildner; Niek F. van Hulst

doi:10.1073/pnas.1308652110

Edited by Lukas Novotny, Eidgenössische Technische Hochschule (ETH) Zurich, ETH Hönggerberg, Zurich, Switzerland, and accepted by the Editorial Board September 23, 2013 (received for review May 7, 2013)

Significance

The focus of ultrafast science is rapidly moving toward increasingly complex systems, both on a fundamental level (such as quantum networks in diamond or excitonic coherence in photosynthesis) and in applied physics (such as multiphoton microscopy in membranes and cells). However, to disentangle the heterogeneous contributions to dynamics in such complex structures, femtosecond time resolution needs to be accompanied by nanometric spatial excitation volumes. Here we present preengineered plasmonic structures to amplitude-phase shape excitation pulses in a designed way, and thus deliver simultaneous deterministic spatial and temporal control. We expect these results to establish the reproducibility that ultrafast plasmonics needs to serve as a reliable and accurate tool for the investigation of femtosecond nanoscopic dynamics in complex systems.

Abstract

Broadband excitation of plasmons allows control of light-matter interaction with nanometric precision at femtosecond timescales. Research in the field has spiked in the past decade in an effort to turn ultrafast plasmonics into a diagnostic, microscopy, computational, and engineering tool for this novel nanometric–femtosecond regime. Despite great developments, this goal has yet to materialize. Previous work failed to provide the ability to engineer and control the ultrafast response of a plasmonic system at will, needed to fully realize the potential of ultrafast nanophotonics in physical, biological, and chemical applications. Here, we perform systematic measurements of the coherent response of plasmonic nanoantennas at femtosecond timescales and use them as building blocks in ultrafast plasmonic structures. We determine the coherent response of individual nanoantennas to femtosecond excitation. By mixing localized resonances of characterized antennas, we design coupled plasmonic structures to achieve well-defined ultrafast and phase-stable field dynamics in a predetermined nanoscale hotspot. We present two examples of the application of such structures: control of the spectral amplitude and phase of a pulse in the near field, and ultrafast switching of mutually coherent hotspots. This simple, reproducible and scalable approach transforms ultrafast plasmonics into a straightforward tool for use in fields as diverse as room temperature quantum optics, nanoscale solid-state physics, and quantum biology.

Footnotes

↵¹To whom correspondence may be addressed. E-mail: daanbrinks{at}fas.harvard.edu or niek.vanhulst{at}icfo.eu.
↵²Present address: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138.
↵³Present address: Experimentalphysik IV, Universität Bayreuth, 95440 Bayreuth, Germany.

Author contributions: D.B. conceived the experiments under supervision of N.F.v.H.; D.B. and M.C.-L. designed the structures; M.C.-L. fabricated and characterized the samples; D.B. and R.H. constructed and calibrated the setup; D.B., M.C.-L. and R.H. conducted experiments; all authors contributed to discussion and interpretation of the results and writing of the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. L.N. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1308652110/-/DCSupplemental.

Freely available online through the PNAS open access option.