Subwavelength structure of the evanescent field of an optical Bloch wave

The authors investigated the evanescent field above a photonic crystal waveguide. In such a waveguide, light is confined in the in-plane direction by a photonic bandgap, and in the out-of-plane direction by total internal reflection. The authors show that the evanescent decay of the field above the waveguide is non-trivial due to the Bloch nature of the mode. As a result complex intensity patterns appear at the nanoscale.