Low-voltage, high extinction ratio carrier-depletion Mach-Zehnder silicon optical modulator

As a result of the low modulation efficiency of carrier-depletion Mach-Zehnder silicon optical modulator, it always needs a high voltage around 6 V, which is very difficult to supply in an integrated high-speed CMOS chip. We demonstrate a carrier-depletion Mach-Zehnder silicon optical modulator which works at a low voltage. Its coplanar waveguide electrode is carefully designed to make sure the electrical wave loss along the device is low. The device operates well at a data rate of 12.5 Gb/s, whose phase-shifter length is 2 mm. Voltages with the swinging amplitudes being 1 V and 2 V are applied to the device with the reverse bias voltages of 0.5 V and 0.8 V. The extinction ratios are 7.67 and 12.79 dB respectively.