1.2 µm and 1.5 µm near-infrared photoluminescence and visible upconversion photoluminescence in GeGaS:Er3+/Ho3+ glasses under 980 nm excitation

Abstract

We report on the Er3+ ↔ Ho3+ optical interaction on the 1.2 and 1.5 µm near-infrared and visible upconversion photoluminescence in Er3+/Ho3+-co-doped GeGaS glasses at pumping wavelength of 980 nm. Since the 980 nm pumping wavelength is off resonance for Ho3+ intra-4f electronic transitions, we have utilized the Er3+ sensitization with observed efficient Er3+ → Ho3+ energy transfer. As a result, the Ho3+ 1.2 µm emission in Er3+/Ho3+-co-doped GeGaS glass has been notably improved while the intense Er3+ 1.5 µm emission has been maintained. The visible upconversion photoluminescence has been observed at 530, 550 and 660 nm and was assigned mainly to intra-4f electronic transitions within Er3+ ions. The overall upconversion photoluminescence intensity significantly increases by addition of Ho3+ ions into GeGaS:Er glass which may be explained by energy transfer processes between Er3+ and Ho3+ ions leading to population of the Er3+ upper energy levels. The Ho3+ 1.2 µm and Er3+ 1.5 µm emission has much potential in telecommunication while the intense visible upconversion photoluminescence in sensing.