Integrated Buried Heaters for Efficient Spectral Control of Air-Clad Microresonator Frequency Combs

Abstract

Integrated heaters are a basic ingredient within the photonics toolbox, in particular for microresonator frequency tuning through the thermo-refractive effect. Resonators that are fully embedded in a solid cladding (typically SiO\textsubscript{2}) allow for straightforward lossless integration of heater elements. However, air-clad resonators, which are of great interest for short wavelength dispersion engineering and direct interfacing with atomic/molecular systems, do not usually have similarly low loss and efficient integrated heater integration through standard fabrication. Here, we develop a new approach in which the integrated heater is embedded in SiO${}_2$ below the waveguiding layer, enabling more efficient heating and more arbitrary routing of the heater traces than possible in a lateral configuration. We incorporate these buried heaters within a stoichiometric Si${}_3$N${}_4$ process flow that includes high-temperature ($>$1000~${}^{\circ }$C) annealing. Microring resonators with a 1~THz free spectral range and quality factors near 10${}^6$ are demonstrated, and the resonant modes are tuned by nearly 1.5~THz, a 5$\times$ improvement compared to equivalent devices with lateral heaters\greg{.} Finally, we demonstrate broadband dissipative Kerr soliton generation in this platform, and show how the heaters can be utilized to aid in bringing relevant lock frequencies within a detectable range.

References in corpus (7)

• Photonic quantum technologies
• Stably accessing octave-spanning microresonator frequency combs in the soliton regime
• Dissipative Kerr solitons in photonic molecules
• Emergent Nonlinear Phenomena in a Driven Dissipative Photonic Dimer
• Dissipative Kerr Solitons in a III-V Microresonator
• On-chip optical parametric oscillation into the visible: generating red, orange, yellow, and green from a near-infrared pump
• Efficiently-coupled microring circuit for on-chip cavity QED with trapped atoms

Cited by in corpus (8)

• Kerr-Induced Synchronization of a Cavity Soliton to an Optical Reference
• High-performance microresonator optical parametric oscillator on a silicon chip
• Fourier synthesis dispersion engineering of photonic crystal microrings for broadband frequency combs
• Strong interactions between integrated microresonators and alkali atomic vapors: towards single-atom, single-photon operation
• Broadband Cavity-Enhanced Kerr Comb Spectroscopy on Chip
• Broadband Visible Wavelength Microcomb Generation In Silicon Nitride Microrings Through Air-Clad Dispersion Engineering
• Scalable low-latency entanglement distribution for distributed quantum computing
• A vapor-cavity-QED system for quantum computation and communication