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



Gregory Moille, Daron Westly, Edgar Perez, Meredith Metzler, Gregory Simelgor, Kartik Srinivasan


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\textsubscript2}) 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$C) annealing. Microring resonators with a 1THz free spectral range and quality factors near 10$^6$ are demonstrated, and the resonant modes are tuned by nearly 1.5THz, a 5$\times$ improvement compared to equivalent devices with lateral heaters 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.
APL Photonics


frequency combs, nonlinear optics, soliton, nanophotonics, fabrication


Moille, G. , Westly, D. , Perez, E. , Metzler, M. , Simelgor, G. and Srinivasan, K. (2022), Integrated Buried Heaters for Efficient Spectral Control of Air-Clad Microresonator Frequency Combs, APL Photonics, [online], , (Accessed May 28, 2024)


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Created November 22, 2022, Updated December 5, 2022