We show the real-space observation of fast and slow pulses propagating inside a photonic crystal waveguide by time-resolved near-field scanning optical microscopy. Local phase and group velocities of modes are measured. For a specific optical frequency we observe a localized pattern associated with a flat band in the dispersion diagram. During at least $3\mathrm{p}\mathrm{s}$, movement of this field is hardly discernible: its group velocity would be at most $c/1000$. The huge trapping times without the use of a cavity reveal new perspectives for dispersion and time control within photonic crystals.

Electrically driven single-photon emitting devices have immediate applications in quantum cryptography, quantum computation and single-photon metrology. Mature device fabrication protocols and the recent observations of single defect systems with quantum functionalities make silicon carbide an ideal material to build such devices. Here, we demonstrate the fabrication of bright single-photon emitting diodes. The electrically driven emitters display fully polarized output, superior photon statistics (with a count rate of >300 kHz) and stability in both continuous and pulsed modes, all at room temperature. The atomic origin of the single-photon source is proposed. These results provide a foundation for the large scale integration of single-photon sources into a broad range of applications, such as quantum cryptography or linear optics quantum computing.

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The eigenfield distribution and the band structure of a photonic crystal waveguide have been measured with a phase-sensitive near-field scanning optical microscope. Bloch modes, which consist of more than one spatial frequency, are visualized in the waveguide. In the band structure, multiple Brillouin zones due to zone folding are observed, in which positive and negative dispersion is seen. The negative slopes are shown to correspond to a negative phase velocity but a positive group velocity. The lateral mode profile for modes separated by one reciprocal lattice vector is found to be different.

We show the first experimental demonstration of multiple heterostructure photonic crystal cavities being coupled together to form a chain of coupled resonators with up to ten cavities. This system allows us to engineer the group velocity of light over a wide range. Devices were fabricated using 193 nm deep UV lithography and standard silicon processing technology. Structures were analysed using both coupled resonator and photonic bandstructure theory, and we highlight the discrepancies arising from subtle imperfections of the fabricated structure.