Lower non-radiative transition probability in Er3+-doped bromide-modified sulfide glasses

New sulfo-bromide glasses of the (60−x)GaS3/2·xGaBr3·10GeS2·30LnS3/2 composition (Ln=La and Er; x=0, 5, 10, 15 and 20) were prepared. Their thermal and optical properties were measured. The bromide-modified glasses exhibited more prominent thermal stability than sulfide glasses of the 60GaS3/2·10GeS2·30LnS3/2 composition (GGLS). As bromides were added to the GGLS glass, the color of the glass changes from red–orange for GGLS glass to pale yellow for bromide-modified sulfide glasses, and consequently the band gaps shifted to shorter wavelengths. As a result, the Er3+ green up-conversion luminescence intensities at around 525 and 550 nm in the bromide-modified glasses became stronger compared with those in pure GGLS glasses.