Clock extraction using an InP/InGaAs HPT direct optical injection-locked oscillator IC with a very wide locking range

This paper presents a new optoelectronic clock recovery circuit that consists of an InP/InGaAs heterojunction phototransistor (HPT) DOILO and a PLC Mach-Zehnder interferometer (MZI). For high-performance, the HPT must have excellent photodetection characteristics as well as sufficient gain to generate an oscillation. An HPT whose layer and process are fully compatible with a high-performance HBT, with an optical gain cutoff frequency of 60 GHz and f/sub max/ of 82 GHz enables us to achieve a high-performance 14-GHz-band HPT DOILO. In addition, the PLC-MZI, which can generate a frequency component of the clock signal from an NRZ data signal by way of an exclusive OR (EX-OR) function in the optical domain, is successfully combined with the HPT DOILO.