Single photons emitted by nano-crystals optically trapped in a deep parabolic mirror

We investigate the emission of single photons from CdSe/CdS dot-in-rods which are optically trapped in the focus of a deep parabolic mirror. Thanks to this mirror, we are able to image almost the full 4$\pi$ emission pattern of nanometer-sized elementary dipoles and verify the alignment of the rods within the optical trap. From the motional dynamics of the emitters in the trap we infer that the single-photon emission occurs from clusters comprising several emitters. We demonstrate the optical trapping of rod-shaped quantum emitters in a configuration suitable for efficiently coupling an ensemble of linear dipoles with the electromagnetic field in free space.Comment: updated version after review, including supplementary material as appendi

Optical trapping of nanoparticles by full solid-angle focusing

Optical dipole-traps are used in various scientific fields, including classical optics, quantum optics and biophysics. Here, we propose and implement a dipole-trap for nanoparticles that is based on focusing from the full solid angle with a deep parabolic mirror. The key aspect is the generation of a linear-dipole mode which is predicted to provide a tight trapping potential. We demonstrate the trapping of rod-shaped nanoparticles and validate the trapping frequencies to be on the order of the expected ones. The described realization of an optical trap is applicable for various other kinds of solid-state targets. The obtained results demonstrate the feasibility of optical dipole-traps which simultaneously provide high trap stiffness and allow for efficient interaction of light and matter in free space.Comment: revised version accepted for publicatio

Trapping rod-shaped quantum emitters in a parabolic mirror for efficient photon collection and light-matter interaction

Effective light-matter interaction requires maximizing the electric field amplitude acting on a matter target while keeping the power of the incident light field constant. One possible option to enhance this coupling is to locate the matter target in a deep parabolic mirror and to focus a suitably shaped light mode. For dipole-like emitters, this light mode is the one of an electric dipole. This thesis is dedicated to interfacing light and nano-particles, which act as single-photon emitters with pronounced linear-dipole character, in a deep parabolic mirror. We identify the use of optical tweezers as a viable approach to the positioning and stable trapping of such emitters at the focus of the parabolic mirror under ambient conditions. Using a linear-dipole mode as the optical trap, we also achieve the alignment of the rod-shaped emitters parallel to the mirror’s axis. This is a necessary prerequisite for the efficient interaction of such particles with light in future experiments. This thesis describes the efforts towards the realization of these results in detail, including a discussion on remaining obstacles and possible approaches to eliminate them.Eine effektive Wechselwirkung zwischen Licht und Materie erfordert die Maximierung der Amplitude des auf das Materieteilchen einwirkenden elektrischen Feldes, während die Leistung des auftreffenden Lichts konstant bleiben soll. Eine Möglichkeit, diese Kopplung zu verbessern, besteht darin, das Teilchen im Brennpunkt eines tiefen Parabolspiegels zu platzieren und eine geeignete Lichtmode auf das Objekt zu fokussieren. Bei dipolartigen Emittern entspricht die dazugehörige Lichtmode der eines elektrischen Dipols. Diese Arbeit befasst sich mit der Wechselwirkung von Licht und Nanopartikeln in einem tiefen Parabolspiegel, die als Einzelphotonenemitter mit ausgeprägtem linearem Dipolcharakter wirken. Die Verwendung einer optischen Pinzette wurde als praktikabler Ansatz für die Positionierung und das stabile Einfangen solcher Emitter im Fokus des Parabolspiegels unter Umgebungsbedingungen identifiziert. Mit einer linearen Dipolmode als optische Falle wurde auch die Ausrichtung von stabförmigen Emittern parallel zur Spiegelachse erreicht. Dies ist eine notwendige Voraussetzung für die effiziente Wechselwirkung solcher Partikel mit Licht in zukünftigen Experimenten. Diese Dissertation beschreibt die Realisierung dieser Ergebnisse im Detail, einschließlich einer Diskussion verbliebener Fragestellungen und deren möglicher Lösungsansätze