Photonic Crystal Multiple Diffraction Observed by Angular-Resolved Reflection Measurements

Angular-resolved reflection measurements suggest that higher-order Miller-index crystal planes of a fcc photonic crystal reflect specularly about the normal to the (111) planes. We suggest that this phenomenon results from a two-step diffraction process where light is first Bragg diffracted by higher-order Miller-index crystal planes and is then two-dimensionally diffracted by periodicities within the (111) planes to produce the specularly diffracted light. This phenomenon is a three-dimensional analog of the well-known Wood's anomaly. © 2009 The American Physical Society.