High-transmission ridge nanoapertures for quantum dot devices*

We report on double-ridge apertures to enhance the coupling between a single quantum dot (QD) and optical field. The double-ridge aperture has two metallic tips protruding inward and facing each other, which work as an effective antenna for a QD just below the tips. We performed FDTD simulation to optimize the apertures, and fabricated them on InAs/GaAs QDs emitting at 960nm. By single-dot PL spectroscopy through the double-ridge aperture, we demonstrated 5-6 times enhancement in PL extraction efficiency, compared to that through a conventional circular aperture. Because our double-ridge aperture works not only as an optical antenna but also as an electrode for a QD, it will be applicable to electrically-driven photon generators or photon detectors.