Octave-spanning supercontinuum generation in a CMOS-compatible thin Si₃N₄ waveguide coated with highly nonlinear TeO₂

Area of Science:

• Nonlinear optics
• Materials science
• Photonics

Background:

• Supercontinuum generation (SCG) is crucial for broadband light sources, with silicon nitride (Si3N4) waveguides being a leading on-chip platform.
• Thick Si3N4 waveguides (>700 nm) are typically needed for SCG, but can cause processing challenges due to high stress and cracks.

Purpose of the Study:

• To achieve efficient SCG in a thinner, moderate-confinement Si3N4 platform.
• To enhance nonlinearity and dispersion properties for broadband SCG applications.

Main Methods:

• Utilized a thinner 400-nm Si3N4 waveguide platform.
• Applied a highly nonlinear tellurium oxide (TeO2) coating to the Si3N4 waveguide.
• Performed numerical simulations to validate experimental findings.

Main Results:

• Achieved octave-spanning SCG from 0.89 to 2.11 µm at a low peak power of 258 W.
• Demonstrated a 2.5-fold increase in the nonlinear parameter (2.5 ± 0.5 W⁻¹m⁻¹) using the TeO2 coating.
• Numerical simulations showed good agreement with experimental results.

Conclusions:

• The hybrid TeO2-Si3N4 waveguides enable highly efficient SCG through dispersion engineering and enhanced nonlinearity.
• This approach offers a promising route for monolithically integrated nonlinear, linear, and active functionalities on a single silicon photonic chip.
• The use of thinner, CMOS-compatible waveguides overcomes processing challenges associated with thicker layers.