A Ga1-xAlxAs monolithic opto-isolator

The performance of a Ga
1-x
Al
x
As monolithic opto-isolator incorporating identical emitter and detector structures is described. The device is fabricated from graded bandgap Ga
1-x
Al
x
As grown by liquid phase epitaxy on a semi-insulating GaAs substrate. Three identical rectangular diode elements are fashioned on the chip; the center element acts as an edge-emitting LED and the outer two bars serve as edge-receiving photodiodes. Air-isolated prototype structures possess optical coupling nearly comparable to typical hybrid devices, and this coupling will be improved by dielectric isolation. Isolation voltages between the LED and the detector exceed 1400 volts. The devices achieve excellent performance in both digital and analog signalling tests.