Optical nanoantennas are capable of controlling the absorption, emission, and scattering of light at the nanoscale . Nanoantennas are generally made up of metals like aluminum, silver, or gold that are known to support plasmonic resonances in the near-infrared/visible/ultraviolet spectral regime, and which can be modified by varying size and shape.
Optical nanoantennas have immense potential in a wide range of applications. Their light-directing and light-harvesting properties can be utilized in:
- Nanoscale sensing
- Spontaneous emission control
- Light trapping in solar cells and anti-reflection coatings
- Fast-writing in magnetic hard disks and localized heating for targeted medicine
- Low-threshold steam generation
- Surface-enhanced Raman scattering
- Color filters for CMOS imaging sensors
Characterization of plasmonic nanoantenna properties presents a challenge in itself which can be attributed to their nanoscale nature. Here, the advanced SPARC cathodoluminescence (CL) system can be used to retrieve optical characteristics with a deep-subwavelength resolution, including:
- Measurement of emission polarization
- Measurement of the angular profile for studying directionality
- Measurement of spatial and spectral distribution of plasmon resonances in a structure with nanoscale spatial resolution
Figure 1 shows an example of how the SPARC CL system can be used in the context of antennas.
Figure 1. (a) Normalized CL spectrum for an Au nanodisk on Si with a diameter of 100 nm and a height of 80 nm. An SEM image is shown as an inset (scale bar: 50 nm). The spectrum is taken by averaging the CL spectrum over the particle. A two-dimensional CL excitation map at λ0 = 560 nm is shown as an inset. The dashed lines indicate the edge of the structure taken from the SEM image. (b) Normalized CL intensity as a function of azimuthal (θ) and zenithal (φ) angles taken at λ0 = 600 nm for excitation on the left side of the structure. The geometry is indicated by the diagram at the right .
- L. Novotny, and N. van Hulst. Antennas for light. Nat. Photon. 5, 83–90 (2011).
- T. Coenen et al. Directional emission from a single plasmonic scatterer. Nat. Commun. 5, 3250 (2014).
This information has been sourced, reviewed and adapted from materials provided by Delmic B.V.
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