Opt. Lett. 36, 3557–3559 (2011)

Many tasks in signal processing severely stretch or are beyond the capabilities of electronic circuitry. The ability to perform such signal processing tasks on high-frequency microwave waveforms, therefore, is one of the key attractions of microwave photonic devices. One of the latest devices to demonstrate this ability is a photonic temporal integrator developed by José Azaña and co-workers in Canada. The device uses a superluminescent diode, a semiconductor optical amplifier, an electro-optic modulator and a cascade of fibre interferometers to generate an output signal that is the cumulative temporal integration of an arbitrary input waveform. The microwave signal to be integrated is used as the drive signal for the electro-optic modulator and the output of the calculation is an optical signal that is collected by a photodetector connected to a sampling scope. Tests show that the device can accurately process signals with bandwidths of ∼36 GHz over a measurement time window of 4 ns, thus significantly outperforming electronic technologies. Such integrators are required for applications in computing, control and communications networks.