Efficient and high-speed silicon Mach-Zehnder modulator at 2 μm wavelengths

Growing research interests have been directed towards the 2-μm waveband, which is considered to be another promising window for fiber and free-space optical communications. However, the signaling beyond 100 Gbit/s was difficult at this waveband due to the limited bandwidth of the available electro-optic modulators. In this study, we demonstrated a 35-GHz silicon photonic Mach-Zehnder Modulator (MZM) fabricated by a standard multi-project wafer process. Up to 100 Gb/s on-chip modulation was experimentally achieved at the wavelength of 1976 nm, which was eventually limited by the bandwidth of the receiver. The modulation efficiency is measured to be 0.82 V·cm. This is a benchmark modulation speed among existing silicon modulators around a 2 µm spectral range.