Continuous and pulsed room temperature lasing behaviour at 1.55 μm on high quality factor photonic crystal microcavities

In this work we show room temperature continuous (CW) lasing at 1.5 mu m in photonic crystal microcavities with a single layer of self-assembled quantum wires (QWRs). Low threshold values in the range of 1-20 mu W (depending on the excitation type, pulsed or CW) have been measured, along high quality factors exceeding Q=55000 using L7-type photonic crystal microcavities. Solid-source molecular beam epitaxy has been used for the synthesis of the InP/InAs epitaxial material comprising a single layer of InAs QWRs. The main axis of the cavity is always parallel to the QWRs, which are more than 1 mu m in length along the [1-10] direction. No lasing has been obtained for L7 cavities with axis parallel to the [110] (i.e., perpendicular to the direction of the QWRs), showing the strong one-dimensional character of the QWRs inside the photonic cavity. Under inhomogeneous pulsed excitation the lasing spectra show asymmetric lineshapes and peak splittings first in the mu eV and later in the meV ranges as the excitation power is increased.