Quantum dot photon source with reduced output pulse duration

摘要

A photon source comprises at least one quantum dot, a carrier injection means and a change of state means. Carriers are injected into the photon source and recombine radiatively within the quantum dot causing a pulse of photon emission. The state of the carriers in the quantum dot is changed after a predetermined length of time which is less than the radiative decay time. This allows the optical output pulse duration W to be selected, thus reducing the jitter in the device. Preferably a pulsed electrical bias is applied to the photon source to change the state of the carriers which includes removal or addition of one or both types of carrier from or to the quantum dot, emptying the quantum dot of all types of carrier, separating the carriers within the source body of moving the carriers into an optically dark state. The carriers may be injected into the quantum dot by electrical or optical excitation.