High Numerical Aperture Real and Fourier Space Investigation of Planar Photonic Devices Operating below the Light Cone

We will demonstrate that Fourier space imaging technique of the light diffracted from a photonic crystal (PhC) device allows the direct measurement of important physical properties of the PhC such as dispersion curves, equi-frequency surfaces, group indices and the characterization of the device performances in a complex environment. Advance techniques based on size effect super-resolution or coupling to an evanescent probe grating allow the extension of the measurement of such quantities even to propagating states lying below the light cone. We will illustrate such technique with three examples: 1) a PhC tile exhibiting self-collimated light propagation; 2) a polarization splitter device and 3) a modified Wl waveguide exhibiting slow light propagation.