Superprism phenomenon in photonic crystals: Guiding the path of light

Photonic crystals can be thought of as 'optical analogues' to electronic semiconductors, and have been widely studied for their periodically-varying indexes of refraction. This allows for controlling the propagation of photons inside the crystals, similar to the way electrons are excited in a semiconductor crystal. The superprism phenomenon is the extremely large angular dispersion experienced by a light beam when entering a photonic crystal. This arises from the anisotropy of the photonic band structure which can be present even in systems without a complete photonic band gap. Here, we describe theoretical and experimental investigation of the superprism effect in three-dimensional macroporous polymer photonic crystals formed from colloidal crystal templates. We explore the extreme sensitivity of the propagation direction to various input parameters, including the input angle, the light frequency, and the composition of the photonic lattice. Such effects can be exploited for sensing and filtering applications.