Highly efficient red, green and blue upconversion luminescence of Eu3+/Tb3+-codoped silicate by femtosecond laser irradiation

Infrared to red, green and blue upconversion luminescence is demonstrated in Eu3+/Tb3+-codoped silicate glass under focused infrared femtosecond laser irradiation. The optical properties show that the emissions come from the 5d → 4f transition of Eu3+ and Tb3+. The relationship between the emission intensity of Eu3+/Tb3+-codoped silicate glass and the pump power reveals that three-photon absorption predominates in the conversion process from the infrared into the visible luminescence. The analysis of the upconversion mechanism suggests that the luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.