Light emitting diode

Details Light emitting diode Light emitting diode

1991-12-27

1993-07-06

Epps, Georgia Y.

Coherent light generators

Particular active media

Semiconductor

372 96, 372 99, 372 49, H01S 319

Patent

active

052260534

ABSTRACT:
This invention embodies a LED in which an optical cavity of the LED, which includes an active layer (or region) and confining layers, is within a resonant Fabry-Perot cavity. The LED with the resonant cavity, hereinafter called Resonant Cavity LED or RCLED, has a higher spectral purity and higher light emission intensity relative to conventional LEDs. The Fabry-Perot cavity is formed by a highly reflective multilayer distributed Bragg reflector (DBR) mirror (R.sub.B .gtoreq.0.99) and a mirror with a low to moderate reflectivity (R.sub.T .perspectiveto.0.25-0.99). The DBR mirror, placed in the RCLED structure between the substrate and the confining bottom layer, is used as a bottom mirror. Presence of the less reflective top mirror above the active region leads to an unexpected improvement in directional light emission characteristics. The use of a Fabry-Perot resonant cavity formed by these two mirrors results in optical spontaneous light emission from the active region, which is restricted to the modes of the cavity. While the bottom DBR mirror reduces absorption by the substrate of that light portion which is emitted toward the substrate, the two mirrors of the resonant cavity reduce the isotropic emission and improve the light emission characteristics in terms of a more directed (anisotropic) emission.

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