The structure of light in photonic crystal waveguides

With a phase-sensitive near-field microscope we measure the propagating of light through a 2D photonic crystal waveguide. We study how the different Bloch harmonics of the propagating light evanescently decay into the air above the waveguide. Furthermore, exploiting the phase sensitivity of our microscope, we are able to reconstruct the electric vector field distribution with subwavelength resolution. In the complex field we observe both time-dependent and time-independent polarization singularities and determine the topology of the surrounding electric field.