A surface plasmon is light that is bound to a metal surface. The main merit of a surface plasmon is that is provides confinement below the diffraction limit. In this thesis, we first study the... Show moreA surface plasmon is light that is bound to a metal surface. The main merit of a surface plasmon is that is provides confinement below the diffraction limit. In this thesis, we first study the excitation and scattering of surface plasmons by subwavelength holes in the metal. Thereafter we show that an array of these hole acts as a surface plasmon laser when the surface plasmons are sufficiently amplified using a semiconductor gain medium Show less
Light is a ubiquitous carrier of information. This information can be encoded in the intensity, direction, frequency and polarisation of the light and, which was described more recently, in its... Show moreLight is a ubiquitous carrier of information. This information can be encoded in the intensity, direction, frequency and polarisation of the light and, which was described more recently, in its orbital angular momentum. Although creating light beams with orbital angular momentum is relatively easy, measuring this property has proven to be difficult. In this thesis we present two fundamental methods to solve this problem. First, we show that by analysing the interference pattern behind a multi-pinhole interferometer, we can determine the phase and amplitude of the light impinging the pinholes, making it possible to determine the orbital angular momentum of the incoming light beam. A multi-pinhole interferometer can be scaled to arbitrary sizes, making it suitable for studying optical fields that stretch out over large distances, that can be expected in, for instance, astrophysics. The second method is based on transforming the helical wave fronts that are associated with light beams with orbital angular momentum to distinguishable, titled wave fronts that can be easily sorted by a lens. This method works for single photons, making it a key piece in a high-dimensional optical communication scheme. This thesis provides theory, simulations and measurements on both detection methods. Show less
This dissertation contains scientific research within the realm of quantum optics, which is a branch of physics. An experimental and theoretical study is made of two-photon interference phenomena... Show moreThis dissertation contains scientific research within the realm of quantum optics, which is a branch of physics. An experimental and theoretical study is made of two-photon interference phenomena in various optical systems. Spatially entangled photon pairs are produced via the nonlinear optical process of spontaneous parametric down-conversion. These entangled photons are then passed through different optical systems to study various aspects of two-photon interference. Firstly, an experimental analysis is made of the high-dimensional entanglement that is present in the orbital angular momentum of the photons. Secondly, we present a comprehensive description of two-photon quantum interference behind a double slit. We demonstrate how to control the quantum correlations and present the first observations of complete two-photon diffraction patterns behind a double slit. Finally, we present pioneering experiments on spatially entangled two-photon states that are scattered of random media. We have observed and theoretically analyzed the structure in the random two-photon interference patterns called two-photon speckle patterns. Spatial entanglement gives two-photon speckle a much richer structure than ordinary one-photon speckle. Our experiments also demonstrate a two-photon interference phenomenon that survives averaging over different realizations of disorder. The latter results are closely related to bosonic, fermionic, and anyonic particle exchange symmetries. Show less
