Bismuth- and aluminum-codoped germanium oxide glasses for super-broadband optical amplification

Abstract

Broadband infrared luminescence from bismuth-doped germanium oxide glasses prepared by a conventional melting–quenching technique was discovered. The absorption spectrum of the glasses covered a wide range from the visible to the near-infrared wavelength regions and consisted of five broad peaks below 370, 500, 700, 800, and 1000 nm. The fluorescence spectrum exhibited broadband characteristics (FWHM) greater than 300 nm with a maximum at 1300 nm pumped by an 808-nm laser. The fluorescence lifetime at room temperature decreased with increasing ${\mathrm{Bi}}_2{\mathrm{O}}_3$ concentration in the glass. Codoping of aluminum and bismuth was indispensable for the broadband infrared luminescence in ${\mathrm{GeO}}_2:\mathrm{Bi}$, Al glass.