Design of an ultra-compact graphene-based integrated microphotonic tunable delay line

The design of a continuously tunable optical delay line based on a compact graphene-based silicon Bragg grating is reported. High performance, in terms of electro-optical switching time (t(switch) < 8 ns), delay range (Delta tau = 200 ps), and figure of merit FOM = Delta tau/A = 1.54x10(5) ps/mm(2), has been achieved with an ultra-compact device footprint (A similar to 1.3 x 10(-3) mm(2)), so improving the state-of-the-art of integrated optical delay lines. A continuous and complete tunability of the delay time can be achieved with a very low delay loss (= 0.03 dB/ps) and a weak power consumption (= 0.05 mW/ps). A flat bandwidth B = 1.19 GHz has been calculated by exploiting the slow-light effect in the device. This performance makes the proposed optical delay line suitable for several applications in Microwave Photonics (MWP), such as beamsteering/beamforming, for which large delay range, flat and wide bandwidth and small volume are required. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement