First demonstration of ~ 5 µm laser action in terbium-doped selenide glass

4.9–5.5 µm laser oscillations were observed in high-purity bulk terbium-doped Ge36Ga5Se59 glass pumped by pulsed 2.93 µm Er:YAG laser. This is the first evidence of laser action corresponding to 7F5–7F6 transition of Tb3+ ions and of mid-infrared lasing in chalcogenide glass host.