Mid-infrared hybrid Si/VO₂ modulator electrically driven by graphene electrodes

Silicon photonic platforms are of significant interest for a variety of applications that operate in the mid-infrared regime. However, the realization of efficient mid-IR modulators, key components in any integrated optics platform, is still a challenging topic. Here, an ultra-compact high-speed hybrid Si/VO₂ modulator operating at a mid-IR wavelength of 3.8 μm is presented. Electrical properties of graphene are employed to achieve a reversible insulating-metal phase transition in VO₂ by electrical actuation. The thermal characteristics of graphene are employed to improve the response time of the VO₂ phase transition through speed up heating and dissipation processes, thus enhancing the modulation speed. Optical and thermal simulations show an extinction ratio of 4.4 dB/μm, an insertion loss of 0.1 dB/μm, and high modulation speed of 23 ns. A larger modulation depth as high as 10 dB/μm can be achieved at the cost of lower modulation speed.