Centi-combs: Low-noise sub-GHz repetition-rate soliton frequency combs from crystalline resonators

Abstract

We demonstrate low-noise Kerr soliton frequency combs with repetition rates below 1~GHz in ultrahigh-Q crystalline magnesium fluoride resonators. Single soliton states with repetition rates of 0.90 GHz, 1.19 GHz, 1.59 GHz, 2.48 GHz, and 4.10 GHz are observed with continuous-wave laser excitation. The near-GHz soliton repetition frequency exhibits a single-sideband phase noise of -137 dBc/Hz at a 100 kHz offset, surpassing state-of-the-art microwave generators. These ``centi-combs'' bridge the gap between conventional mode-locked lasers and microresonator frequency combs, providing a new route towards real-time sampling, optical-to-microwave synchronization, and hybrid optical clock networks in a compact form. This work expands the operational range of Kerr soliton microcombs from the terahertz to the sub-gigahertz domain, opening new frontiers for frequency comb technologies.

4 pages, 3 figures

References in corpus (29)

• Optical frequency comb generation from a monolithic microresonator
• Temporal solitons in optical microresonators
• Parallel convolution processing using an integrated photonic tensor core
• Microresonator solitons for massively parallel coherent optical communications
• Microresonator Soliton Dual-Comb Spectroscopy
• Broadband electro-optic frequency comb generation in an integrated microring resonator
• An Integrated-Photonics Optical-Frequency Synthesizer
• Ultrafast optical ranging using microresonator soliton frequency combs
• Soliton Microcomb Range Measurement
• Universal dynamics and controlled switching of dissipative Kerr solitons in optical microresonators
• Nanophotonic soliton-based microwave synthesizers
• Octave Spanning Frequency Comb on a Chip
• Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators
• Applications of integrated optical microcombs
• High-order coherent communications using mode-locked dark-pulse Kerr combs from microresonators
• Monolithic piezoelectric control of soliton microcombs
• 300 GHz wave with attosecond-level timing noise
• Ultralow-Noise Photonic Microwave Synthesis using a Soliton Microcomb-based Transfer Oscillator
• Emerging material systems for integrated optical Kerr frequency combs
• Foundry manufacturing of tight-confinement, dispersion-engineered, ultralow-loss silicon nitride photonic integrated circuit
• Spectral purification of microwave signals with disciplined dissipative Kerr solitons
• Microresonator soliton dual-comb imaging
• Dissipative Kerr soliton microcombs for FEC-free optical communications over 100 channels
• Versatile tuning of Kerr soliton microcombs in crystalline microresonators
• Ultrahigh-Q crystalline microresonator fabrication with only precision machining
• Microresonator Soliton Frequency Combs in the Zero-Dispersion Regime
• Mechanically actuated Kerr soliton microcombs
• GHz fundamental mode-locking of a highly integrated Er-doped all-fiber ring laser
• Systematic dispersion engineering of crystalline microresonators for broadband and coherent frequency comb generation