Premium
Microcavity effects in ensembles of silicon quantum dots coupled to high‐ Q resonators
Author(s) -
Bianucci Pablo,
Zhi Yanyan,
Marsiglio Frank,
Silverstone Josh,
Meldrum Al
Publication year - 2011
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201000379
Subject(s) - quantum dot , laser linewidth , luminescence , physics , photoluminescence , quantum dot laser , optoelectronics , condensed matter physics , materials science , optics , semiconductor laser theory , semiconductor , laser
Microcavities can be used to control the spectral properties of ensembles of quantum dots. In this work, spherical microcavities with quality ( Q ) factors as high as 3 × 10 8 in air were coated with a layer of fluorescent silicon quantum dots. After coating, the transmission Q factors decreased to approximately 10 6 or slightly lower, while the luminescence Q ‐factors ( Q PL ) reached a maximum of ∼4000. While these are the highest Q PL values yet reported for Si QDs, Q PL was always orders of magnitude lower than the intrinsic cavity Q . One reason for the difference has its origin in the quantum dot emission linewidth, which is associated only with the Q PL and not with the cold cavity (intrinsic) Q . Essentially, the Q factor in luminescence experiments arises from the spontaneous emission rate enhancements or suppressions experienced by the dot in the cavity. We developed a general model to calculate the luminescence spectrum and decay dynamics for an inhomogeneously broadened ensemble of quantum dots with arbitrary emission linewidths weakly coupled to an optical cavity. Using this model and comparing it with experiment, we show that the respective values of the luminescence quality factors and the cold cavity quality factors can be used to determine an effective quantum dot emission linewidth without the need for single particle spectroscopy. In the case of Si quantum dots, the room temperature emission linewidth may be as small as a few meV at room temperature.