Bismuth nanoparticle-doped bulk glasses as an active medium for a photonic device

Abstract

The thermo-optical properties of a nano-composite glass consisting of a bulk germanate matrix with embedded Bi nanoparticles have been investigated. Heating and cooling cycles around the Bi melting point reveal that the nanoparticles melt and solidify reversibly remaining encapsulated in the matrix. Optical transmission spectra as a function of temperature show significant contrast upon cycling. Furthermore this contrast has a marked wavelength dependence whose origin is explained by the change of the bismuth dielectric function upon melting. These results open the possibility of designing a versatile thermo-optical switch by selecting suitable matrices and by controlling the size and the shape of the Binanoparticles.