US Patent 7772551 - Variable refractive index element formed using quantum dots

http://ip.com/patent/US7772551

This patent from Toshiba suggests a refractive optical switching device based on a quantum dot material. Claim 1 reads:

1. A refractive index variable element, comprising:

a structure including quantum dots having discrete energy levels and a dielectric matrix surrounding the quantum dots; and

an electron discharger discharging an electron from the quantum dots through the dielectric matrix to convert the quantum dots into cations.