Mixing up-conversion excitation behaviors in Er3+/Yb3+-codoped aluminum germanate glasses for visible waveguide devices

A mixing up-conversion excitation phenomenon in Er3+/Yb3+-codoped aluminum germanate (Na2O–MgO–Al2O3–GeO2, NMAG for short) glasses for K+–Na+ ion-exchanged waveguides was observed and characterized. The green and red up-conversion luminescence of Er3+ is due to a two-photon excitation process under low-power excitation of a 974 nm diode laser, however, with increasing the pumping power, the green emission turns to follow a combination of two- and three-photon excitation effects while the red one still agrees with a two-photon excitation law. Under high-power pumping, owing to potential thermal effect, the population ratio between the 2H11/2 and 4S3/2 levels adjusts acutely, which results in a distinct exhibition in 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 emission transitions. Green transmission trace has been observed in K+–Na+ ion-exchanged Er3+/Yb3+-codoped NMAG glass waveguide and it provides an original reference in developing visible waveguide amplifiers and lasers.