Cathodoluminescence for Geology

Cathodoluminescence for nanophotonics and plasmonics

Cathodoluminescene-sem-SPARC

Cathodoluminescence (CL) imaging is a powerful method for studying nanostructures and optical phenomena at nanoscale. The electron beam acts as a very pure local excitation source. The hyperspectral light-emission maps produced with cathodoluminescence illustrate the local density of electromagnetic states, a quantity that determines how well light couples to matter and vice versa. Furthermore, the directionality and polarization of emission can rigorously be measured with angle-resolved images, thus providing yet more insight into the optical properties of nanostructures.

This makes the technique highly relevant to the field of nanophotonics. It is applicable to metallic as well as dielectric and semiconductor nanostructures, including nanoparticles, nanowires, metamolecules, metasurfaces, and photonic crystals. These structures find applications in (bio)sensing, fluorescence enhancement, non-linear optics, low-threshold steam generation, LED’s, solar cells, integrated photonics, lasers and much more.

 


  

angular patterns

Angular patterns of plasmonic antennas acquired with angle-resolved cathodoluminescence

Studying plasmonic nanoantennas

Optical nanoantennas have the ability to control the emission, absorption, and scattering of light at the nanoscale. Nanoantennas are often composed of metals such as gold, silver, or aluminium that support plasmonic resonances in the visible/ultraviolet/near-infrared spectral regime, and which can be tuned by varying shape and size.

Using the cathodoluminescence imaging one you can retrieve optical properties with deep-subwavelength resolution, including:

  • measuring the spectral and spatial distribution of plasmon resonances in a structure with nanoscale spatial resolution,

  • measuring the angular profile to study directionality,

  • measuring the polarization of emission

Studying semiconductor nanoparticles

Cathodoluminescence spectroscopy can be used to directly visualize the internal modal structure of semiconductor nanoparticles. This is done to better understand how the nanoparticles and nanowires confine light. 

Combining particles in complex geometries enables more tunability of the optical response and is key for their integration with a macroscopic device, such as an LED or solar cell. Electromagnetic coupling between the particles plays a critical role in determining the optical properties in these systems and leads to mode hybridization, for instance. Such coupling effects can be visualized with cathodoluminescence. 

 

semiconductor nanoparticles

(a) Schematic of the silicon nanoparticle geometry. (b) CL spectrum (magenta dots) averaged over all excitation positions on the particle. An SEM micrograph of the particle is shown as inset (scale bar is 150 nm). (c) Spatial CL maps showing the modal excitation profiles for the peaks in (b) derived from a single hyperspectral CL dataset.

  

photonic-crystal2

Studying photonic crystals

In integrated photonics on-chip generation, manipulation, and detection of light is extremely important. Photonic crystals (PCs) are of interest in integrated photonics due to their ability to guide, confine, and slow down light on small length scales. 

By using the SPARC cathodoluminescence (CL) system one is able to retrieve optical properties with deep subwavelength resolution, including:

  • measuring the spectral and spatial distribution of cavity resonances, waveguide modes, and extended modes in continuous crystals,

  • measuring the angular profile to study the dispersion of light in the PC
 

Sign up for an online demo

Are you ready to enhance your research?

Sign up for a demonstration of one of our systems and learn about cathodoluminescence technique which can be used in your research. 

During the demonstration you will learn:

  • how cathodoluminescence can be applied in your field
  • what possibilities it can open up for you
  • how it can be combined with other techniques