  Optical modulators are at the heart of optical communication links. Ideally,
they should feature low insertion loss, low drive voltage, large modulation
bandwidth, high linearity, compact footprint and low manufacturing cost.
Unfortunately, these criteria have only been achieved on separate
occasions.Based on a Silicon and Lithium Niobate hybrid integration platform,
we demonstrate Mach-Zehnder modulators that simultaneously fulfill these
criteria. The presented device exhibits an insertion loss of 2.5 dB,
voltage-length product of 2.2 Vcm, high linearity, electro-optic bandwidth of
at least 70 GHz and modulation rates up to 112 Gbit/s. The high-performance
modulator is realized by seamless integration of high-contrast waveguide based
on Lithium Niobate - the most mature modulator material - with compact,
low-loss silicon circuits. The hybrid platform demonstrated here allows for the
combination of 'best-in-breed' active and passive components, opening up new
avenues for enabling future high-speed, energy efficient and cost-effective
optical communication networks.
