Light control with ordered and disordered nanophotonic media

Abstract

In this dissertation experimental results are presented on controlling light with nanophotonic media. The first part describes research on forbidden zones of light: frequency gaps in photonic crystals. Polarization-resolved and position-dependent reflectance spectroscopy on silicon two- and three-dimensional photonic crystals revealed broad stop bands with record-high reflectivity exceeding 60%. A general diffraction phenomenon, called sub-Bragg diffraction, has been discovered and explained. Angle-averaged, polarization-resolved and position-dependent spectra reveal a common stop band of up to 16% gap-to-midgap frequency ratio for inverse woodpile photonic crystals, forming a strong experimental signature of the presence of a complete photonic band gap. The second part of this dissertation presents experiments on light propagation near the band edge in GaAs photonic-crystal waveguides. Phase-sensitive near-field microscopy was used to map light propagation with sub-wavelength resolution, revealing periodic field patterns consisting of superpositions of optical Bloch modes. A Bloch mode reconstruction algorithm was tested to extract and study individual Bloch modes. In the slow-light regime, the periodic field patterns are perturbed by Anderson-localized modes that form due to multiple-scattering on intrinsic disorder. A detailed dispersion diagram has been measured for a specific photonic-crystal waveguide. A method was introduced to reconstruct the density of optical states, constituting to the first experimental demonstration of an optical Lifshitz tail. The third part of this dissertation describes experiments towards adaptive quantum optics. A high-rate entangled-photon source was developed based on type-II spontaneous parametric down conversion. Single-photon propagation in multiple-scattering media has been controlled with wavefront shaping. The probability that a photon arrives at a target output speckle spot after propagation through a layer of white paint has been increased 30-fold. Wavefront shaping techniques on classical light have been successfully implemented to use opaque scattering media as a balanced optical beam splitter. This is the first demonstration of a multiple input and output wavefront shaping optimization. This work can be extended to program quantum interference in disordered photonic media in general, forming the outlook of adaptive quantum optics.