Photonic crystal light-emitting diodes

A novel LED design employing a 2D periodic photonic crystal host is demonstrated theoretically to yield extraction efficiencies approaching 100 percent. Specifically, a thin slab of 2D photonic crystal is shown to alter drastically the radiation pattern of spontaneous emission. By eliminating all guided modes at the transition frequencies, spontaneous emission can be coupled entirely to free space modes, resulting in a greatly enhanced extraction efficiency. Such structures might provide a solution to the long-standing problem of poor light extraction form high refractive-index semiconductors in light-emitting diodes.