Demonstration of passive, nonlinear, and active devices on a hybrid photonic platform.

Abstract

The monolithic fabrication of passive, nonlinear, and active functionalities on a single chip is highly desired in the wake of the development and commercialization of integrated photonic platforms. However, the co-integration of diverse functionalities has been challenging as each platform is optimized for specific applications, typically requiring different structures and fabrication flows. In this article, we report on a monolithic and complementary metal-oxide-semiconductor CMOS-compatible hybrid wafer-scale photonics platform that is suitable for linear, nonlinear, and active photonics based on moderate confinement 0.4-µm-thick Si₃N₄ waveguiding layer coated with a ∼0.4-µm thick TeO₂ film. This platform offers four main advantages, which are (1) ensuring reduced stress and film cracking for scalable fabrication by using thin Si₃N₄, (2) allowing polarization-insensitive single-mode operation at telecom wavelengths, (3) enhancing waveguide nonlinearity and allowing dispersion engineering by adding the TeO₂ film coating, and (4) achieving amplification and lasing through incorporation of rare-earth dopants during the TeO₂ film deposition step. We present the design and experimental measurement of TeO₂-coated ∼0.4-µm-thick Si₃N₄ microring resonators with internal Q factors of 7.5 × 10⁵ and 5.2 × 10⁵ for TE and TM polarizations, respectively. The experimental results show that the dispersion of TeO₂-coated ∼0.4-µm-thick Si₃N₄ waveguides can be engineered between normal and anomalous by adjusting the thickness of the TeO₂ layer. For a 1.6-µm wide, 500 µm bend radius ring resonator with a ∼0.4-µm-thick TeO₂ coating, anomalous dispersion values of 25 and 78 ps/nm·km were measured at 1552 nm wavelength for the TE and TM-modes, respectively, and the onset of Kerr comb generation was observed. Also, by applying an Er-doped TeO₂ coating, an optical amplifier with TE and TM net gain and 5.5 dB net internal gain at 1533 nm in a 6.7-cm-long waveguide and a microdisk laser were demonstrated. These results show a promising route to monolithic integration of passive, nonlinear, and active functionalities via hybrid waveguides on standard silicon photonic platforms.