Superprism phenomenon in three-dimensional macroporous polymer photonic crystals

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. Strong anisotropy can be present even in systems without a complete photonic band gap. Here, we describe a theoretical investigation of the superprism effect in three-dimensional macroporous polymer photonic crystals formed from colloidal crystal templates. From the complete photonic band structure, an equal-energy surface ~dispersion surface! is obtained. The propagation direction inside the photonic crystal is determined by the gradient of this surface. Using this formalism, 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.