Concentration quenching in erbium implanted alkali silicate glasses
A comparison is made of photoluminescence properties of six sodalime and alkali-borosilicate glasses implanted with Er to concentrations as high as 1.4x lO21 at./cm3. Clear photoluminescence (PL) spectra around 1.54 mm, due to the 4I13/2-> 4I15/2 transition in Er3+ are observed, of which the shape depends on the host glass composition. PL lifetimes in the range of 0.9-12.6 ms are found, depending on glass and Er concentration. In borosilicate glass, implantation-induced defects remain after annealing and cause quenching of the Er luminescence due to a direct coupling to the Er. Such defects are not present in Er-implanted sodalime glass after annealing. In both types of glass the luminescence lifetime decreases strongly with concentration due to a concentration quenching effect in which energy migration takes place due to energy transfer between Er ions, followed by quenching at hydroxyl groups. Concentration quenching via this mechanism is less strong in the borosilicates than in the sodalime glasses, but because of the quenching effect of implantation-induced defects in borosilicates these glasses are not suitable for optical doping by ion implantation.
