High bit rate clock recovery of NRZ data by all-optical processing in a semiconductor optical amplifier and direct optical injection locking of a self-oscillating phototransistor

In this letter, we describe a novel all-optical processing technique of nonreturn-to-zero signals in a semiconductor optical amplifier, which enables spectral enhancement at the bit rate frequency. The processed optical signal is used for direct optical injection locking of an oscillator based on a heterojunction bipolar phototransistor. Clock extraction at 10 Gb/s and potential operation at 40 Gb/s and beyond are demonstrated.