Localized excitation of InGaAs quantum dots by utilizing a photonic crystal nanocavity

We have studied excitation wavelength dependence of light emission from InGaAs quantum dots (QDs) embedded in high-quality-factor photonic crystal nanocavities. The light emission of the cavity mode around 1μm was very weak with below-band-gap excitation in the InGaAs wetting layer. However, the emission of the lowest-order cavity mode was strongly enhanced when the excitation wavelength was resonant with higher-order cavity modes. This phenomenon can be attributed to the local intensity enhancement of the excitation light which couples with the cavity mode. The on-resonant excitation technique selectively and efficiently excites only the QDs in the cavity without undesirable background emission.