Abstract
Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.
Highlights
Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances
Developments of different methods for measuring either the electric or the magnetic local density of states of nano-optical devices have been on going by employing scanning near-field optical microscopy (SNOM) aperture probes[11,12,13,14,15,16,17,18,19,20,21], and more recently by using aperturless scattering SNOM or molecules which undergo detectable magnetic dipole transitions[22,23,24]
The local SNOM probe acts as an optical antenna, converting the electromagnetic near-field into propagating radiation and vice versa, with a net energy transfer efficiency that defines the throughput of the antenna and with an imaging spatial resolution bounded by the size of the probe that interacts with the near-field
Summary
Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Several developments have improved the SNOM sensitivity, versatility and resolution, a complete www.nature.com/scientificreports understanding of tip-light-sample interactions, and which components of the electromagnetic field are collected by SNOM probes, is still lacking This issue depends on many subtle aspects such as the exact tip geometry, the orientation of electric and magnetic dipoles with which the probes can be approximated, the light polarization, and more in general the experimental configuration. Structures such as micro-disks, micro-waveguides, nanoparticles, nanoplasmonic resonators, and photonic crystal nanocavities (PCNs) are able to localize electromagnetic fields in very small mode volumes. They have been so far used to directly detect either the electric or the magnetic field component of light, and most of them rely on resonant structures with a limited spectral bandwidth
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
