The plasmonic BTO-on-SiN platform - beyond 200 GBd modulation for optical communications

An integrated photonics platform that offers high-speed modulators in addition to low-loss and versatile passive components is highly sought after for different applications ranging from AI to next-generation Tbit/s links in optical fiber communication. For this purpose, we introduce the plasmonic BTO-on-SiN platform for high-speed electro-optic modulators. This platform combines the advantages provided by low-loss silicon nitride (SiN) photonics with the highly nonlinear barium titanate (BTO) as the active material. Nanoscale plasmonics enables high-speed modulators operating at electro-optical bandwidths up to 110 GHz with active lengths as short as 5 µm. Here, we demonstrate three different modulators: a 256 GBd C-band Mach-Zehnder (MZ) modulator, a 224 GBd C-band IQ modulator - being both the first BTO IQ and the first IQ modulator on SiN for data communication - and finally, a 200 GBd O-band racetrack (RT) modulator. With this approach we show record data rates of 448 Gbit/s with the IQ modulator and 340 Gbit/s with the MZ modulator. Furthermore, we demonstrate the first plasmonic RT modulator with BTO and how it is ideally suited for low complexity communication in the O-band with low device loss of 2 dB. This work leverages the SiN platform and shows the potential of this technology to serve as a solution to combat the ever-increasing demand for fast modulators.