Octave-spanning supercontinuum generation in a CMOS-compatible thin Si<sub>3</sub>N<sub>4</sub> waveguide coated with highly nonlinear TeO<sub>2</sub>
Hamidu M. Mbonde, Neetesh Singh, Bruno L. Segat Frare, Milan Sinobad, Pooya Torab Ahmadi, Batoul Hashemi, Dawson B. Bonneville, Peter Mascher, Franz X. Kärtner, Jonathan D. B. Bradley
Abstract
Supercontinuum generation (SCG) is an important nonlinear optical process enabling broadband light sources for many applications, for which silicon nitride (Si 3 N 4 ) has emerged as a leading on-chip platform. To achieve suitable group velocity dispersion and high confinement for broadband SCG the Si 3 N 4 waveguide layer used is typically thick (>∼700 nm), which can lead to high stress and cracks unless specialized processing steps are used. Here, we report on efficient octave-spanning SCG in a thinner moderate-confinement 400-nm Si 3 N 4 platform using a highly nonlinear tellurium oxide (TeO 2 ) coating. An octave supercontinuum spanning from 0.89 to 2.11 µm is achieved at a low peak power of 258 W using a 100-fs laser centered at 1565 nm. Our numerical simulations agree well with the experimental results giving a nonlinear parameter of 2.5 ± 0.5 W −1 m −1 , an increase by a factor of 2.5, when coating the Si 3 N 4 waveguide with a TeO 2 film. This work demonstrates highly efficient SCG via effective dispersion engineering and an enhanced nonlinearity in CMOS-compatible hybrid TeO 2 –Si 3 N 4 waveguides and a promising route to monolithically integrated nonlinear, linear, and active functionalities on a single silicon photonic chip.