Compact Silicon-Rich SiN/LiNbO3 Mach Zehnder and Microring Modulators

We report on the demonstration of Mach Zehnder and microring modulators based on a hybrid silicon-rich SiNx /LiNbO3 waveguide at a wavelength of 1550nm. By using low-temperature PECVD deposition, we obtained non-stoichiometric silicon nitride with a refractive index of ~2.66 which was used to fabricate racetrack ring resonators of 80µm bending radius with a 100 µm long modulating section. We measured intrinsic quality factors up to \(1.1\times {10}^{5}\) , corresponding to propagation losses of 1–1.2 dB/cm in the range 1500 nm–1600 nm. A 5 mm-long SiNx/LiNbO3 Mach Zehnder modulator with a 2.8 V.cm efficiency and a 30 dB extinction ratio has been demonstrated.