Photoluminescence of Point Defects in Silicon Dioxide by Femtosecond Laser Exposure

Abstract

The nature of the radiation-induced point defects in amorphous silica is investigated through online photoluminescence (PL) under high intensity ultrashort laser pulses. Using 1030 nm femtosecond laser pulses with a repetition rate of 1 kHz, it is possible to study the induced color centers through their PL signatures monitored during the laser exposure. Their generation is driven by the nonlinear absorption of the light related to the high pulse peak powers provided by femtosecond laser, allowing to probe the optical properties of the laser exposed region. The experiment is conducted as a function of the laser pulse power in samples with different OH contents. The results highlight the different interaction regimes attained by varying the irradiation conditions for various chemical compositions. Moreover, the online measurements are combined with postmortem characterization of the damaged area, via phase contrast microscopy, Raman and steady-state PL spectroscopies, highlighting the potential of these online femtosecond tests to provide additional knowledge to the postmortem technique ones.