Photonic chip-based optical frequency comb using soliton Cherenkov radiation.

Area of Science:

• Photonics
• Nonlinear Optics
• Integrated Photonics

Background:

• Optical solitons are light pulses maintaining shape through balanced nonlinearity and dispersion.
• Higher-order dispersion in solitons can lead to dispersive wave emission via soliton Cherenkov radiation.
• Soliton Cherenkov radiation is crucial for supercontinuum generation and frequency metrology.

Purpose of the Study:

• To generate continuously circulating temporal dissipative Kerr solitons in a dispersion-engineered silicon nitride microresonator.
• To investigate the emission of soliton Cherenkov radiation due to higher-order dispersion.
• To develop a compact, on-chip optical frequency comb with stabilized phase for metrology and spectroscopy.

Main Methods:

• Utilized a continuous wave-pumped, dispersion-engineered, integrated silicon nitride microresonator.
• Generated temporal dissipative Kerr solitons.
• Observed red-shifted soliton Cherenkov radiation due to higher-order dispersion.

Main Results:

• Successfully generated continuously circulating temporal dissipative Kerr solitons.
• Observed red-shifted soliton Cherenkov radiation.
• Produced a fully coherent optical frequency comb spanning two-thirds of an octave.
• Achieved sub-Hertz level phase stabilization of the frequency comb.

Conclusions:

• The integrated silicon nitride microresonator effectively generates dissipative Kerr solitons and soliton Cherenkov radiation.
• The resulting broad and coherent optical frequency comb has significant potential for frequency metrology and spectroscopy.
• This device offers a pathway towards compact, on-chip frequency comb technology.