The riddle of orange-red luminescence in Bismuth-doped silica glasses.

For over the past two decades it has been believed that the intense orange-red photoluminescence in Bismuth-doped materials originates from Bi[Formula: see text] ions. Based on the results from magnetic circular polarization experiments, we demonstrate that this hypothesis fails for Bismuth-doped silica glasses. Our findings contradict the generally accepted statement that the orange-red luminescence arises from [Formula: see text] [Formula: see text] [Formula: see text] transition in a divalent Bismuth ion.

On the nature of photoluminescence in Bismuth-doped silica glass.

We report on the investigation of Bismuth-doped pure silica glass without other co-dopant by the tech- nique of magnetic circular dichroism (MCD), which allows the direct probing of the ground state of optical centres. Taking into account the results of conventional optical spectroscopy, we show that the observed MCD bands belong to the centre responsible for the red photoluminescence in this material. Measurements of the temperature and field dependences indicate that the MCD effect is caused by the even-electron system.