Recent development in a high-speed silicon optical modulator based on reverse-biased pn diode in a silicon waveguide

We review the recent development of a high-speed silicon optical modulator based on electric-field-induced carrier depletion effect in a silicon-on-insulator waveguide containing a reverse-biased p–n junction. The device design, fabrication and characterization are presented. To obtain efficient optical modulation, we design a sub-micrometer size silicon waveguide phase shifter based on both semiconductor device modeling and photonic circuit modeling. By employing traveling-wave drive that allows co-propagation of electrical and optical signals along the waveguide, we demonstrate a high-frequency modulator with 3 dB optical response bandwidth of 30 GHz and data transmission up to 40 Gb s−1. Such a high-speed silicon modulator will be a key component for silicon-photonic-integrated circuits for future computing I/O applications.