Weyl semimetals (WSMs) is an emerging class of materials possessing unique electromagnetic properties that are not commonly achievable with conventional metals and semiconductors. The exotic phenomena emerging from the so-called Weyl nodes in WSMs where valence and conduction bands cross in single points and electrons effectively behave as Weyl fermions make WSMs very interesting for novel photonic applications in areas of non-linear optics, photovoltaics, THz electrooptics, and detection. In this work, we explore the enhancement of WSM nonlinear response by merging WSMs with the concept of plasmonics, i.e. nano-optics utilizing deeply subwavelength collective oscillations of free electrons in metallic nanostructures, and metasurfaces where arrays of plasmonic nanoantennas are used to control the phase, amplitude and polarization of the incident light. Since electrons possess non-trivial electronic states in WSMs, plasmonics could enable the observation of unique optoelectrical phenomena in WSMs with the added benefit of creating nonlinear optical elements that are smaller than the diffraction limit. Here, we realized a nanopatch plasmonic antenna array on the WSM TaAs crystal to demonstrate the enhanced non-linear optical response from TaAs. By developing a large-scale, non-destructive method of fabricating the antenna array, we address the challenge of WSM integration with photonic devices. We demonstrate a six-fold increase of the second-harmonic generation (SHG) from the Weyl semimetal TaAs surface by distributing plasmonic silver nanoantennas on TaAs.
We experimentally demonstrate high coupling of light to surface polaritons by means of an optimized scatterer placed at a suitable distance from a polariton-supporting surface. Specifically, we consider poorly-absorbing gold disks acting as nearly-perfect resonant scatterers, which we separate from a gold film by means of a dielectric silica spacer. This configuration leads to resonant coupling between externally incident light and plasmon polaritons in the film with associated cross sections that approach and surpass the fundamental limit ~λ2 imposed by the light wavelength λ. Our method introduces a disruptive, efficient way to solve the in/out-coupling problem in nanophotonics.
Significant miniaturization of high-Q supercavity systems with planar technology requires novel coupling structures that excite the desired set of resonant modes. We review the physics of bound states in the continuum (BICs) of open, high-index dielectric resonators, excited by new complex sources that enable a controlled interference in the system. We show that, in avoided-crossing regimes associated with quasi-BICs, the controlled retardation of inducing currents can bring up the Q-factors beyond the state-of-the-art levels in optimized, fully-symmetric systems. We illustrate our theory with proof-of-concept experiments in microwaves, comparing high-index dielectric resonators excited by microstrip structures with different mode complexity.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.