Stimulated emission and amplification coefficient for quantum dots arrays under optical pumping

Stimulated emission from quantum dots arrays has been observed under optical pumping. The emission has been observed from the ground state for electrons (λ ≈ 1.31 μm) and from two higher levels (λ ≈ 1.21 μm, 1.12 μm). The measured values of the amplification coefficient are rather high, up to 15 ÷ 17 cm
^-1
. Procedure of the amplification coefficient measurements in the active media has been discussed.