Sub-Volt Silicon-Organic Electro-optic Modulator With 500 MHz Bandwidth

Lowering the operating voltage of electro-optic modulators is desirable for a variety of applications, most notably in analog photonics and digital data communication. In particular for digital systems such as CPUs, it is desirable to develop modulators that are both temperature-insensitive and compatible with typically sub-2 V CMOS electronics; however, drive voltages in silicon-based Mach-Zehnder interferometers (MZIs) currently exceed 1.8 V. Here, we show an MZI modulator based on an electro-optic polymer-clad silicon slot waveguide, with a halfwave voltage of only 0.69 V (corresponding to a 0.62 V(·)cm modulation figure of merit), and a bandwidth of 500 MHz. We also show that there are paths to significantly improve both the bandwidth and drive voltage.