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arXiv · 2608.17277

Nanophotonic dispersion engineering in tantala-based microresonators with ultralow-loss claddings

Alexa R. Carollo·Atasi Dan·Jizhao Zang·Haixin Liu·Nitesh Chauhan·Scott B. Papp
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Abstract

Integrated photonics optimized to leverage low loss, nonlinear-optical processes and optoelectronic integration requires robust optical cladding materials and associated fabrication process flows. We develop low-loss silicon dioxide (SiO$_2$) claddings with tantalum pentoxide (Ta$_2$O$_5$, tantala) integrated photonics to realize robust, high intrinsic quality factor ($Q_i$) microresonators and photonic-crystal resonators (PhCRs) for soliton microcomb generation. Specifically, we introduce a full-wafer, low-temperature process compatible with two tantala-based films: pure tantala and an amorphous metal-oxide mixture of titanium dioxide (TiO$_2$, titania) and tantala. Combining tantala with titania enhances the film's resistance to damage from the SiO$_2$ cladding deposition process, offering access to high $Q_i$ above $4 \times 10^6$ in fully cladded microresonators. Our platform supports low-loss edge couplers, group-velocity dispersion engineering by waveguide geometry, access to nanophotonic structures particularly to control phase-matching, and high dimensional tolerance in devices across an entire wafer. Using the platform, we explore the generation of high-efficiency, dark-soliton microcombs with repetition frequency from 50 GHz to 500 GHz, which supports applications such as photonic artificial intelligence acceleration, electronic signaling, and optical data communication.

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Alexa R. Carollo, Atasi Dan, Jizhao Zang, Haixin Liu, Nitesh Chauhan, Scott B. Papp. 2026-08-18. Nanophotonic dispersion engineering in tantala-based microresonators with ultralow-loss claddings. https://arxiv.org/abs/2608.17277

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