Extending chip-based Kerr-comb to visible spectrum by dispersive wave engineering

Area of Science:

• Photonics
• Nonlinear Optics
• Materials Science

Background:

• Anomalous group velocity dispersion is crucial for generating bright solitons and wideband Kerr frequency combs.
• Extending frequency comb spectra to visible wavelengths is challenging due to normal dispersion in conventional materials.

Purpose of the Study:

• To numerically demonstrate a wideband frequency comb spanning near-infrared to visible wavelengths.
• To overcome the limitations of normal dispersion in photonic materials for visible light generation.

Main Methods:

• Utilizing an optimized over-etched silicon nitride waveguide for blue-shifted anomalous dispersion.
• Employing a coupled resonator architecture to enhance power transfer to shorter wavelengths via radiative dispersive waves.
• Modulating dispersion in the coupled resonator architecture to tune the comb spectrum.

Main Results:

• Demonstrated a wideband frequency comb from approximately 1200 nm to 650 nm.
• Achieved a wideband blue-shifted anomalous dispersion in the silicon nitride waveguide.
• Showcased a tunable dispersive Cherenkov radiation peak near the overall comb peak, only 10 dB below.

Conclusions:

• The proposed micro-resonator design enables wideband frequency combs extending into the visible spectrum.
• The approach effectively utilizes anomalous dispersion and radiative dispersive waves to overcome material limitations.
• Tunable dispersive Cherenkov radiation offers potential for novel visible light sources.