We report a compact 2×2 Mach-Zehnder interferometer （MZI） electro-optic switch fabricated on a silicon- on-insulator using standard complementary metal-oxide semiconductor （CMOS） processes. With a short modu- lation arm length of 200μm, the crosstalk is reduced to -22 dB by the new modulation scheme of push-pull modulation with a pre-biased π2 phase shift. The new modulation scheme can also work with a fast switching time of about 5.4 ns.
A high-speed silicon modulator with broad optical bandwidth is proposed based on a symmetrically configured Mach- Zehnder interferometer. Careful phase bias control and traveling-wave design are used to improve the high-speed perfor- mance. Over a broadband wavelength range, high-speed operation up to 30 Gbit/s with a 4.5 dB-5.5 dB extinction ratio is experimentally demonstrated with a low driving voltage of 3 V.
A novel high-efficiency focusing non-uniform grating coupler is proposed to couple light into or off silicon photonic chips for large-scale silicon photonic integration. This kind of grating coupler decreases the transition length of the linking taper between the grating and the single-mode waveguide by at least 80%. The radian of the grating lines and the size of the taper are optimized to improve the coupling efficiency. An experimental coupling efficiency of ~ 68% at 1556.24 nm is obtained after optimization and the whole size of the grating is 12 μm × 30 μm, with a very short taper transition of ~15 μm long.
