Semiconductor nanocavities are of interest for their potential as threshold-less lasers and high-speed modulated sources. When cavity volumes are shrunk below the size of a cubic wavelength, the rate of spontaneous emission can be enhanced. This so-called Purcell enhancement has lead to the misconception that the modulation speed of nanocavity lasers can be significantly enhanced beyond that of their classical (large volume) counterparts. Here, by performing a detailed analysis, we show that the modulation bandwidth can, indeed, be increased by the Purcell effect, but that this enhancement occurs only when the device is biased below lasing. The maximum bandwidth is also shown to be inversely proportional to the modal volume, with speeds approaching 100's of GHz for cavity volumes of 0.01 cubic half-wavelengths. Hence, with recent advances in plasmonic nanocavity design, we propose nano-LEDs as extremely high-bandwidth, low power light engines for optical interconnects.
Project end date: 02/02/11