Eigenstates of photonic crystal structures visualized in real space and in k-space

Photonic crystal structures allow an unprecedented control of light on length scales equivalent to the wavelength. The intricate interaction of light and the periodic lattice can lead to phenomena like localization, negative refraction and slow light. In order to understand the optical behaviour of such novel structures, an investigation of the underlying photonic eigenstates is crucial, since the propagation of light through them is governed by their photonic eigenstates and the coupling between these states. Here we investigate the propagation of light pulses through a complex photonic crystal device in real-time. Analysis of the photonic eigenstates in k-space allows different states to be identified. By tracking the evolution of the eigenstates in both k-space and time, we uncover the dynamics of the eigenstates and their mutual coupling directly on femtosecond time-scales.