Very high radiance edge-emitting LED

In this paper we describe a new light-emitting diode (LED) whose radiance is 1000 W/cm
²
sr, an order of magnitude higher than any previous LED. The LED is an (AlGa)As double-heterojunction edge-emitting structure. This structure acts as a waveguide for the internally generated light, and with appropriate Al concentration difference at the heterojunctions (
\Deltax \approx 0.3
) and active region width (∼500Å), the radiation pattern perpendicular to the junction can be less than 30° (FWHM). For fiber-optic communications this LED is capable of coupling 850 μw, at a coupling loss of only -10 dB into a 0.14-numerical-aperture (NA), 90-μm-diam low-loss fiber. The LED is capable of being directly modulated at 250 MHz and has a spectral width of less than 300 Å.