Stimulated emission from optically pumped quantum dots

Stimulated emission from optically pumped quantum dot arrays has been studied experimentally at room temperature. We have demonstrated stimulated emission on interband transitions from the ground level in a quantum well (? ? 1.31 ?m) and from two excited states (? ? 1.21 and 1.12 ?m). The gain coefficient of the transitions has been evaluated using exposed strips of variable length. The gain coefficients thus obtained are rather large, up to 15?17 cm-1 (at ? ? 1.31 ?m). A procedure is discussed for measuring large gain coefficients (above 10 cm-1) of active media. The stimulated emission from the excited states is found to be sharply suppressed with increasing strip length.