High-speed GaAs-(GaAl)As DH LED's with output waveguide structure for optical communications

High-speed GaAs-(GaAl)As DH edge-emitting LED's with an output waveguide structure and a reversed p-n junction for current confinement are described. A cutoff frequency of 115 MHz and a radiance of 1100 W/sr cm²at a diode current of 200 mA have been measured. The output power at the end of a fiber pigtail is about 200 µw with a driving current of 200 mA (core diameter of fiber = 60 µm and numerical aperture NA = 0.2). The coupling efficiency between the diode and a single fiber amounts to 10 percent. Factors affecting both the radiative output and the modulation characteristics are analyzed and discussed.