Phase locking between light pulses and a resonant tunneling diode oscillator

Abstract
We report the phase locking of an oscillating GaAs/AlGaAs resonant tunneling diode (RTD) to a train of optical pulses. Locking was achieved by direct illumination of a specially designed RTD with a diode laser pulse train. Locking occurs at all rational frequency ratios and with excitation energies as low as 0.1 pJ/pulse for the principle lock.