Maximum gains of laser-pumped glasses activated with Yb3+ and Er3+ ions

A theoretical analysis is made of the main factors limiting the maximum attainable gains in laser-pumped glasses (⁴I_13/2–⁴I_15/2 transition in Er³⁺ ions) activated with Yb³⁺ and Er³⁺ ions. It is shown that, in principle, the spectroscopic and lasing parameters of the glasses make it possible to obtain gains of up to 0.8–1 cm^–1, the main limiting factor being superradiance. Experimental measurements were made of the short pulse gains in phosphate-based glasses activated with Yb³⁺ and Er³⁺ ions at the highest possible pumping levels and the results were compared with the theoretical analysis.