Excited-state absorption measurement in Ge-doped SiO₂ glass

Optical absorption change in the microsecond order in oxygen-deficient Ge-doped SiO₂ glass was measured as a function of time just after photon irradiation from a KrF excimer laser. The absorption above 3 eV was found to decay with a similar time constant as that of the luminescence at 3.1 eV. From this, it is confirmed that the observed absorption change is due to the excitation of electrons from the lowest excited triplet state to an upper state. By taking account of the energy range of the absorption, there is a high possibility that the upper state is the conduction band.