Capacitive silicon optical modulators for high-speed and high-efficiency operation

The silicon optical modulator is a key component in a high speed optical data link. To advance the modulator performance beyond the popular carrier depletion based devices, we have produced a capacitive device which is instead based upon the accumulation of free carriers either side of a thin insulating layer positioned in the middle of the waveguide. Such a device has a superior efficiency compared with the carrier depletion approach allowing compactness and improved power consumption whilst retaining high speed operation and CMOS compatibility.