The effects of lanthanum addition on optical characteristics of Ge−Ga−S−AgI chalcogenide glasses

Tm3+-doped Ge−Ga−S−AgI chalcogenide glasses with the addition of La2S3 have been fabricated. The effects of La2S3 on the glass structure and the Tm3+-doped infrared emission property have been discussed. The results show that incorporation of La in the Ge−Ga−S−AgI glass matrix induces the dissociation of Ge-Ge metal bonds and transforms the [S3Ge-GeS3] bonds to GeS4 tetrahedra. A new peak at about 230 cm−1 is detected in Raman spectra and a redshift at the visible absorbing cut-off edge is observed with introduction of La2S3. The La2S3-modified glasses exhibit enhanced emission intensity in both 1.46 μm and 1.8 μm emission bands and have larger solubility of rare-earth because of substitution mechanism of Tm3+ for La3+ ions. The introduction of high Tm concentration into glasses induces the attenuation of emission intensity. This phenomenon is correlated with the recurrence emission quenching effect.