Coupled photonic-crystal cavities and quantum-wire microlasers

Strong optical confinement implemented with 2D photonic-crystal (PhC) microcavities provides a powerful tool for controlling the features of light-matter interaction. Combined with nanostructures such as quantum wells, quantum wires (QWRs) or quantum dots, the PhC cavities - efficiently controlling spontaneous emission [1] - are envisaged to bring superior semiconductor-laser performance [2], which could be exploited for applications in low-power-consumption integrated optoelectronics. Furthermore, inter-cavity optical coupling may allow for optimizing the laser output power [3] and realizing ultra-fast switching devices [4]. Here, we present experimental and numerical studies of directly coupled L₃-type PhC microcavities that employ monolithically embedded site-controlled QWRs acting as local internal light sources. Using microphotoluminescence (PL) experiments [5], it is shown that such PhC system supports coupled modes with distinct resonant wavelengths and delocalized optical fields. It is also demonstrated that the cavity losses of these modes may ldquosplitrdquo as well, in general. Furthermore, we demonstrate single-mode QWR-PhC microlasers. Low thresholds (~1 muW) and relatively high spontaneous-emission coupling factors (beta ~ 0.3) are achieved. Lasing is established based on power-dependent linewidth narrowing [6] and time-resolved photon dynamics [7]. This work provides grounds for the development of more complex PhC systems for experiments in quantum physics [8] and microlasers [4].