Power-efficient ultra-broadband soliton microcombs in resonantly-coupled microresonators

Area of Science:

• Photonics and optical engineering
• Integrated optics
• Nonlinear optics

Background:

• Microresonator solitons are key for miniaturizing optical frequency combs.
• High power consumption limits their spectral span and repetition rate, hindering practical applications.
• Current waveguide-coupled designs face power bottlenecks for octave-spanning combs.

Purpose of the Study:

• To introduce resonant-coupling as a method to reduce pump power requirements for soliton microcombs.
• To overcome the limitations of conventional designs for achieving wide spectral spans and low repetition frequencies.
• To enable chip-scale octave-spanning optical frequency combs for practical applications.

Main Methods:

• Implemented a resonant-coupling scheme for soliton microcombs.
• Compared performance against conventional waveguide-coupled designs.
• Investigated spectral span and repetition frequency under reduced pump power.

Main Results:

• Achieved a threefold increase in spectral span for high-power soliton microcombs.
• Demonstrated up to a tenfold reduction in repetition frequency for octave-spanning operation.
• Showcased compatibility with laser integration for reliable, turnkey soliton generation.

Conclusions:

• Resonant-coupling significantly reduces pump power consumption in soliton microcombs.
• This approach overcomes the power bottleneck, enabling practical octave-spanning combs at microwave repetition rates.
• The technology paves the way for portable optical clocks, advanced data links, and field spectrometers.