Gain-switched semiconductor laser driven soliton microcombs

Area of Science:

• Photonics and Optical Engineering
• Semiconductor Laser Technology
• Nonlinear Optics

Background:

• Dissipative Kerr solitons in microcombs are typically generated using continuous-wave lasers.
• Existing methods suffer from low energy efficiency and high optical power thresholds, especially for microwave repetition rates.
• Integrated hybrid microcombs offer turnkey operation but face limitations in power efficiency.

Purpose of the Study:

• To develop a more energy-efficient method for generating soliton microcombs.
• To reduce the optical power threshold for microcomb generation, particularly for microwave frequencies.
• To enable robust and stable soliton generation in microresonators using pulsed laser pumping.

Main Methods:

• Actively switching the bias current of injection-locked III-V semiconductor lasers to create pulsed pumping.
• Utilizing picosecond laser pulses to pump crystalline and integrated microresonators.
• Implementing phase engineering on the pulsed pumping scheme to control soliton dynamics.

Main Results:

• Achieved soliton microcomb generation with stable repetition rates using pulsed pumping.
• Reduced the required average pumping power by one order of magnitude to a few milliwatts.
• Demonstrated robust soliton generation and stable trapping on intracavity pulse pedestals through phase engineering.

Conclusions:

• Pulsed pumping of microresonators significantly enhances energy efficiency and lowers power thresholds for soliton microcombs.
• Phase engineering of pulsed pumps is crucial for robust soliton generation and stable trapping.
• This approach advances energy-efficient chipscale microcombs for microwave applications.