Cross section of the4I11/2–4I13/2laser transition in Er3+ions in yttrium–erbium–aluminum garnet crystals

Measurements were made of the ratio of the luminescence energies represented by the 4I11/2–4I13/2 and 4I11/2–4I15/2 transitions in Er3+ ions in (Y1–xErx)3Al5O12 crystals. The Einstein coefficients of these transitions were also determined. The cross section of the 4I11/2–4I13/2 (X2–Y6) stimulated emission transition was measured. The concentration dependences of the absolute quantum efficiencies of the luminescence from the 4I11/2 and 4I13/2 levels were obtained.