Formation of Infrared Femtosecond Laser Induced Colour Centersin Tb³⁺-Doped and Tb³⁺/Ce³⁺-Codoped Heavy Germanate Glasses

Formation of infrared femtosecond laser induced colour centers was observed in the Tb³⁺-doped and Tb³⁺/Ce³⁺-codoped heavy germanate glasses. A rectangle scanning was made by focusing the laser beam inside the glass samples. A three-dimensional yellowish block was created from the path and it corresponded to the appearance of broad absorption bands in the absorption spectra. Irradiation induced absorption coefficient μ (λ) was used to characterize the distribution of radiation induced colour centers in the samples, whose peak was located at 380 nm and extended to the longer wavelength. Ce³⁺ ions were found not only to inhibit the formation of colour centers, but also to enhance the recovery.