Travelling-Wave Mach-Zehnder Modulator as a Temporal Integrator and a Time-Gate Isolator

This letter demonstrates that a commercial travelling-wave Mach-Zehnder modulator is a versatile device. Next to being a modulator, it is also able to function as an electro-optical temporal integrator with an integration window twice as long as its propagation delay. Using the similar principle and being driven by a periodic RF frequency, the modulator is able to perform as an optical time-gate isolator that blocks any reverse-travelling lightwave, but simultaneously allows forward-travelling periodically-pulsed optical signals to pass. In the experiment, sub-nanosecond forward-travelling time gates and reverse-travelling optical power extinction >20 dB are successfully demonstrated.