We report on the study of the spectroscopic properties in Ytterbium-Terbium (Yb3+-Tb3+) co-doped calcium lithium borate (CaLiBO) glasses, with the study’s focus being on the upconversion process. Intensity parameters Ωλ for CaLiBO:Tb3+ are determined by the Judd-Ofelt method to be Ω2 = 15.5 × 10-20 cm2, Ω4 = 1.90 × 10-20 cm2 and Ω6 = 3.69 × 10-20 cm2. We have also obtained electric-dipole (and magnetic-dipole) radiative transition probabilities, branching ratios, and lifetime for the Tb3+:5D4 and 5D3 levels. In addition, an evaluation of the upconversion processes by luminescence and time-resolved spectroscopy were carried out. The upconversion rise and decay times, energy transfer probability from Yb3+ to Tb3+ ions, and the efficiency of the processes that depopulate the Tb3+:5D4 level after resonantly pumping the Yb3+:2F5/2 level were estimated. Our results showed that a cooperative energy transfer (CET) from two Yb3+ ions to one Tb3+ ion is the origin of the Tb3+ upconversion luminescence in the visible region. While, CET followed of the cross relaxation or/and excited state absorption is responsible for the upconversion luminescence in the ultraviolet region.

Materials specially designed for photonics have been at the vanguard of chemistry, physics and materials science, driven by the development of new technologies. One particular class of materials investigated in this context are glasses, that in principle should exhibit high third order optical nonlinearities and fast response time, whose optical properties can be tailored by compositional changes, such as, for instance, the incorporation of metallic nanoparticles to explore plasmon resonances. Simultaneously to the development of novel materials, and motivated by the need of device miniaturization, direct laser writing by femtosecond pulses has been used to advanced processing of glasses. Such method allows fabricating high resolution three-dimensional optical devices, as well as to produce spatially localized metal nanoparticles. This review paper initially presents results on the nonlinear optical characterization of special glasses, in addition to progresses on the use of femtosecond laser micromachining for producing waveguides and spatially confined metal nanoparticles.