LED for single photons

The paper describes on natural approach of generating single photons is to adapt conventional semiconductor light emission technology. A single photon source can be fabricated by integrating a single quantum dot into a conventional light emitting diode (LED). Such a device has the advantages of being rugged and compact, while eliminating the need for a pump laser and its cumbersome alignment with the quantum emitter. The device consists of a GaAs p-i-n junction with a layer of InAs quantum dots grown inside the intrinsic region. Electroluminescence from a single quantum dot is isolated by a combination of restricting the emitting area using an aperture in the opaque top contact and spectral filtering. Single photon emission pulses are generated by driving the diode with sub-nanosecond electrical pulses. Measurements of the second order correlation function of the dot electroluminescence demonstrate an order of magnitude reduction in the number of multi-photon emission pulses compared to a laser of the same average intensity. The maximum repetition rate of the single photon emitting diode is limited by the exciton lifetime in the dot to be several hundred MHz.