Role of interfaces in heterophotonic crystals for manipulation of photons

The manipulation of photons via artificially introduced line and point defects in photonic crystals is becoming important for various scientific and engineering applications. Here, we propose a concept for realizing high extraction of the photons from a line-defect waveguide to free space through a point-defect cavity in a photonic crystal. A configuration of heterophotonic crystals with different lattice constants is introduced, and the heterostructure interface plays an important role, acting as a nearly perfect but selective mirror for photons of a specific energy. Furthermore, the enhancement of extraction efficiency is experimentally demonstrated in the fabricated device.