Recent advances in high speed silicon optical modulator

High-speed silicon optical modulator is one of key components for integrated silicon photonic chip aiming at Tb/s data transmission for next generation communication networks as well as future high performance computing applications. In this paper we review the recent development of the silicon modulator. In particular, we present a high-speed and highly scalable silicon optical modulator based on the free carrier plasma dispersion effect. The fast refractive index modulation of the device is due to electric-field-induced carrier depletion in a Silicon-on-Insulator waveguide containing a reverse biased pn junction. To achieve high-speed performance, a traveling-wave design is employed to allow co-propagation of electrical and optical signals along the waveguide. We demonstrate high-frequency modulator optical response with 3 dB bandwidth of ~20 GHz and data transmission up to 30 Gb/s. We also highlight the future device optimization for 40 Gb/s and beyond.