Erbium-mediated photoconductivity of Ga–Ge–S–Se : Er3+chalcogenide glasses

Photoconductivity mediated by erbium ions in chalcogenide glasses Ga–Ge–S has been found. The conductivity of glasses undoped and doped with erbium has been studied under irradiation by laser light at λ = 813 nm. In both cases the optical band-gap energy exceeds by several times the laser photon energy. It has been observed that the exposure to sub-band-gap light does not change the conductivity of the undoped glass, whereas it leads to a significant increase in the conductivity of the glass doped with erbium. We propose a two-photon mechanism of the photoconductivity in this glass, where erbium accumulates laser energy and then transfers it nonradiatively to the glass matrix (energy backtransfer).