High speed optical modulator based on silicon slotted-rib waveguide

A high-speed electro-optic modulator based on CMOS compatible silicon waveguide is proposed. The optical waveguide in silicon is formed by creating a slot in a rib structure that results in a strong optical confinement with an acceptably low propagation loss. The proposed design of slotted-rib waveguide with a traveling-wave electrode facilitates an efficient optical modulation in silicon. Taking the advantage of velocity matched between optical and microwave modes, a high-speed operation up to 70 Gbps with an extinction ratio of approximate to 4.9 dB is reported at a peak to peak voltage of 3 V-pp under a reverse bias of 4 V. An insertion loss of 3.1 dB is obtained for a 4 mm long device.