AlGaAs soliton microcombs at room temperature.

Area of Science:

• Optics and Photonics
• Materials Science
• Nonlinear Optics

Background:

• Soliton mode locking in microcavities is key for integrated frequency comb systems.
• Aluminum Gallium Arsenide (AlGaAs) offers high optical nonlinearity for low-threshold comb generation.
• AlGaAs's strong thermo-optic effect typically requires cryogenic temperatures for stable soliton formation.

Purpose of the Study:

• To demonstrate soliton generation in AlGaAs microresonators at room temperature.
• To investigate the role of the thermo-optic effect in stabilizing soliton formation.
• To achieve low-pump-threshold, high-repetition-rate soliton crystals.

Main Methods:

• Fabrication of high-Q AlGaAs microresonators.
• Experimental demonstration of soliton mode locking at room temperature.
• Characterization of soliton crystals and single soliton generation.
• Verification in a silica micro-toroid resonator.

Main Results:

• First demonstration of room-temperature soliton generation in AlGaAs microresonators.
• The thermo-optic effect was shown to stabilize high-repetition-rate solitons.
• Single soliton and soliton crystal generation achieved with sub-milliwatt optical pump power.
• Successful replication in a silica micro-toroid.

Conclusions:

• Room-temperature soliton generation in AlGaAs is feasible and overcomes previous thermal limitations.
• The AlGaAs platform is suitable for integration with semiconductor lasers for frequency comb applications.
• This approach is generalizable to other high-Q resonator materials.