High-speed silicon modulator with band equalization

Electro-optic modulation up to 70 Gbit/s has been demonstrated using a silicon Mach-Zehnder modulator with a bias voltage of -1.5 V. In a wide frequency range from DC, an increasing input impedance of the modulator was designed to equalize its electro-optic frequency response. Without a bias voltage, the 3 dB bandwidth was measured as 35 GHz and it is predicted to be as high as 55 GHz at -3 V bias. Frequency responses of the modulator operated with counter-propagating waves were tested to verify the proposed prediction model.