Stably accessing octave-spanning microresonator frequency combs in the soliton regime

Abstract

Microresonator frequency combs can be an enabling technology for optical frequency synthesis and timekeeping in low size, weight, and power architectures. Such systems require comb operation in low-noise, phase-coherent states such as solitons, with broad spectral bandwidths (e.g., octave-spanning) for self-referencing to detect the carrier-envelope offset frequency. However, stably accessing such states is complicated by thermo-optic dispersion. For example, in the Si3N4 platform, precisely dispersion-engineered structures can support broadband operation, but microsecond thermal time constants have necessitated fast pump power or frequency control to stabilize the solitons. In contrast, here we consider how broadband soliton states can be accessed with simple pump laser frequency tuning, at a rate much slower than the thermal dynamics. We demonstrate octave-spanning soliton frequency combs in Si3N4 microresonators, including the generation of a multi-soliton state with a pump power near 40 mW and a single-soliton state with a pump power near 120 mW. We also develop a simplified two-step analysis to explain how these states are accessed in a thermally stable way without fast control of the pump laser, and outline the required thermal properties for such operation. Our model agrees with experimental results as well as numerical simulations based on a Lugiato-Lefever equation that incorporates thermo-optic dispersion. Moreover, it also explains an experimental observation that a member of an adjacent mode family on the red-detuned side of the pump mode can mitigate the thermal requirements for accessing soliton states.

References in corpus (4)

• Mode-locked ultrashort pulse generation from on-chip normal dispersion microresonators
• Bringing short-lived dissipative Kerr soliton states in microresonators into a steady state
• Strong polarization mode coupling in microresonators
• Phase Steps and Hot Resonator Detuning in Microresonator Frequency Combs

Cited by in corpus (13)

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• Photonic flywheel in a monolithic fiber resonator
• Inter-mode breather solitons in optical microresonators
• Hybrid InP and SiN integration of an octave-spanning frequency comb
• pyLLE: a Fast and User Friendly Lugiato-Lefever Equation Solver
• Two-colour dissipative solitons and breathers in microresonator second-harmonic generation
• Coupled-mode theory for microresonators with quadratic nonlinearity
• Soliton trapping and comb self-referencing in a single microresonator with ${\chi }^{(2)}$ and ${\chi }^{(3)}$ nonlinearities
• Soliton crystals in optical Kerr microresonators in the presence of thermo-optic effects
• Frequency combs with multiple offsets in THz-rate microresonators
• Tailoring Broadband Kerr Soliton Microcombs via Post-Fabrication Tuning of the Geometric Dispersion