Exploiting Ultralow Loss Multimode Waveguides for Broadband Frequency Combs

Abstract

Low propagation loss in high confinement waveguides is critical for chip-based nonlinear photonics applications. Sophisticated fabrication processes which yield sub-nm roughness are generally needed to reduce scattering points at the waveguide interfaces in order to achieve ultralow propagation loss. Here, we show ultralow propagation loss by shaping the mode using a highly multimode structure to reduce its overlap with the waveguide interfaces, thus relaxing the fabrication processing requirements. Microresonators with intrinsic quality factors (Q) of 31.8 $\pm$ 4.4 million are experimentally demonstrated. Although the microresonators support 10 transverse modes only the fundamental mode is excited and no higher order modes are observed when using nonlinear adiabatic bends. A record-low threshold pump power of 73 $\mu$W for parametric oscillation is measured and a broadband, almost octave spanning single-soliton frequency comb without any signatures of higher order modes in the spectrum spanning from 1097 nm to 2040 nm (126 THz) is generated in the multimode microresonator. This work provides a design method that could be applied to different material platforms to achieve and use ultrahigh-Q multimode microresonators.

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Cited by in corpus (15)

• Applications of integrated optical microcombs
• Platicon microcomb generation using laser self-injection locking
• Foundry manufacturing of tight-confinement, dispersion-engineered, ultralow-loss silicon nitride photonic integrated circuit
• Realizing an entanglement-based multi-user quantum network with integrated photonics
• Dual-mode microresonators as straightforward access to octave-spanning dissipative Kerr solitons
• Measurements and modeling of atomic-scale sidewall roughness and losses in integrated photonic devices
• Foundry compatible, efficient wafer-scale manufacturing of ultra-low loss, high-density Si${}_3$N${}_4$ photonic integrated circuits
• Fabrication-Robust Silicon Photonic Devices in Standard Sub-Micron Silicon-on-Insulator Processes
• Hyperparametric oscillation via bound states in the continuum
• Protected generation of dissipative Kerr solitons in supermodes of coupled optical microresonators
• Near octave-spanning perfect soliton crystals in AlN microresonators
• Proposal for stable atom trapping on a GaN-on-Sapphire chip
• Intermodal Brillouin scattering in solid-core photonic crystal fibers
• Ultra-fast and accurate multimode waveguide design based on dataset-based eigenmode expansion method
• Engineered mode coupling in high-Q microresonators enables deterministic low-repetition-rate soliton microcombs