Beam splitter with tunable power ratio achieved by a composite structure

摘要

Controlling the propagation of light by using a square lattice photonic crystal (PC) is investigated. Beam bending is accomplished by gradually varying the orientation of dielectric rods. The beam redirection relies on gradual modification of PC structural parameters which make the group velocity location dependent. A Y-shaped beam splitter is then designed by means of a composite structure consisting of two graded PCs. The splitting ability of the beam splitter is further discussed. We demonstrate that one input beam can be split into two output beams. The equal and unequal energy splitting are obtained.