Optical control of 14 GHz MMIC oscillators based on InAlAs/InGaAs HBTs with monolithically integrated optical waveguides

An In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As heterojunction bipolar transistor (HBT) with a novel integrated optical waveguide for light input has been developed. Detailed modeling is used to validate the design and simulate the coupling of light from the waveguide into the device. Fabricated waveguide-HBT devices exhibited cutoff frequencies of f/sub T/=32 GHz and f/sub max/=48 GHz with 56% of the guided light being converted to photocurrent. Fabricated MMIC oscillators operating at 13.9 GHz exhibited direct optical controllability in the form of optical tuning and injection locking. This is the highest reported frequency for direct optical injection locking in an HBT-based oscillator.