High-speed silicon Mach-Zehnder optical modulators with large optical bandwidths (Conference Presentation)

Silicon photonics is considered as a promising technology to overcome the difficulties of the existing digital and analog optical communication systems, such as low integration, high cost, and high power consumption. Silicon optical modulator, as a component to transfer data from electronic domain to optical one, has attracted extensive attentions in the past decade. In this paper, I will review our efforts in developing high-speed silicon Mach-Zehnder optical modulators with large optical bandwidths. Firstly, I will introduce how to optimize the modulation efficiency, optical loss, electro-optical bandwith of the silicon optical modulator. The fabricated silicon Mach-Zehnder optical modulator has an electro-optical bandwidth of up to 39.8 GHz. When the device is optically biased at the quadrature pont, it has the dynamic extinction ratios of 6.5 dB, 5.9 dB and 5.2 dB at the speeds of 40 Gbps, 50 Gbps and 64 Gbps for OOK modulation. Secondly, I will introduce two types of silicon PAM-4 optical modulator. One is driven by a PAM-4 electrical signal and the other is driven by two binary electrical signals with different peak-to-peak voltages. Both two devices can generate PAM-4 optical signals at the speed of over 30 Gbaud in the wavelength of 1525-1565 nm. The corresponding bit error rates could reach as low as ~10−6, which is below the hard-decision forward error correction threshold of 3.8×10-3. Finally, I will introduce a silicon 16-QAM optical modulator, which is based on four Mach-Zehnder modulators driven by four binary electrical signals. With the simple electrical driving configuration, the device generates a 16-QAM optical signal at 20 Gbaud with an error vector magnitude of 13.7%.