VINSE member Jason Valentine’s work published in ACS Photonics was featured in C&EN magazine and Nature Materials
06/15/2015 “Simple Process Creates Near-Perfect Mirrors Out Of A Metamaterial
Photonics: A layer of self-assembled particles allows researchers to etch an almost-perfect reflector that might be used in telescopes and lasers out of silicon
By Katherine Bourzacx
[…] Last year, Jason Valentine, a mechanical engineer at Vanderbilt University, and colleagues demonstrated a third kind of mirror—a metamaterial—that combined the simplicity of metal films with the near-perfection of Bragg reflectors (Appl. Phys. Lett. 2014, DOI: 10.1063/1.4873521). Metamaterials are engineered to have properties, typically derived from nanoscale patterning, that do not occur in the bulk material. They made their reflector by patterning a silicon wafer’s surface with an array of silicon cylinders a few hundred nanometers in diameter. Each of the cylinders acted like a tiny resonator for particular light frequencies—analogous to the way certain sound frequencies will make a tuning fork hum. By adjusting the size of the cylinders, Valentine could control how well they reflected light of a given frequency. This mirror reflected more than 99% of light at the peak wavelength. […]
6/23/2015 “Silicon photonics: Large-scale dielectric metasurfaces”
Researchers develop a simple and low-cost fabrication method for the production of large-scale all-dielectric metasurfaces, which exhibit near-perfect reflectivity in the telecommunications spectral window.
By Nicolas Bonod
Mirrors are undoubtedly the most common and widely used optical components for controlling light propagation. Most of them are composed of a thin metallic layer coated on a thick substrate. As metals experience losses in the optical and near-infrared frequencies, these metallic mirrors tend to absorb a small amount of light that prevents them from achieving perfect reflection. A way to realize near-perfect mirrors is by the use of lossless materials, such as dielectrics. Now, writing inACS Photonics, Jason Valentine and colleagues present a method to fabricate large-scale dielectric mirrors composed of a single layer of silicon particles grown on a silicon-on-insulator substrate1. Light reflection relies in this case on a resonant interaction between light and silicon particles, which exhibit electric and magnetic spectral modes.