High-performance Mach–Zehnder modulator using tailored plasma dispersion effects in an ITO/graphene-based waveguide

Abstract

Abstract A high-performance electro-optic Mach–Zehnder modulator (MZM) with outstanding characteristics is proposed. The MZM is in a push-pull configuration that is constructed using an ITO/graphene-based silicon waveguide. A novel idea for engineering of the plasma dispersion effect in an ITO/graphene-based waveguide is proposed so that the modulation characteristics of the MZM are highly improved. Plasma dispersion effects of ITO and graphene layers are tailored in such a way that a large difference between real parts of guided mode effective index of the two arms is achieved while their corresponding imaginary parts are equal. As a result, a very low $${{\mathrm {V}}}_{\pi }L_{\pi }$$ V π L π of $$10 \, \hbox {V} \upmu \hbox {m}$$ 10 V μ m is achieved. To the best of our knowledge, this is one of the lowest $${{\mathrm {V}}}_{\pi }L_{\pi }$$ V π L π reported for an electro-optic modulator. In addition, the proposed modulator exhibits a very high extinction ratio of more than 30 dB, low insertion loss of 2.8 dB and energy consumption of as low as 10 fJ/bit, which are all promising for optical communication and processing systems.