Research

We develop integrated quantum photonic devices for generating, manipulating, and distributing quantum states of light, targeting scalable technologies for quantum communication, computation, and sensing.

Using the second-order nonlinearity and electro-optic response of lithium niobate, we build broadband photon-pair sources and demonstrate high-visibility on-chip two-photon (Hong–Ou–Mandel) interference.

We have also implemented quantum key distribution over field-deployed optical fiber using lithium niobate photonic circuits, showing that integrated quantum photonics can operate outside controlled laboratory conditions.

Our long-term goal is to deliver these functions as stable, field-ready building blocks for practical quantum photonic systems.

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We study nonlinear optical processes for compact and efficient integrated light sources.

Our main effort is second-order frequency conversion in thin-film and periodically poled lithium niobate, including second-harmonic generation, sum-frequency generation, and spontaneous parametric down-conversion. In high-Q racetrack resonators we drive cascaded harmonic generation with a continuous-wave laser alone, producing multiple on-chip wavelengths without pulsed or high-power pumps.

We also explore Kerr nonlinear optics in emerging low-loss materials such as tantalum pentoxide (Ta₂O₅), extending the range of platforms available for integrated nonlinear photonics. Pairing these materials with high-Q resonators, we aim to build versatile light sources for both classical and quantum applications.

We develop the photonic platforms, optical interfaces, and fabrication technologies that make our quantum and nonlinear devices practical.

A central focus is efficient optical coupling: our 3D mode-size converters match the large mode of an optical fiber to the guided mode of a photonic chip—improving fiber-to-chip and chip-to-chip efficiency and alignment tolerance—complemented by anti-reflection treatment at the optical interfaces.

Rather than pursuing ever-tighter optical confinement, we are developing a microphotonics approach that enlarges the optical mode on low-loss, quartz-based platforms (such as Ta₂O₅ on fused quartz) to achieve higher fabrication tolerance, reproducibility, and device yield.

Building on this, we pursue modular, reconfigurable architectures in which independently optimized modules—a quartz-based routing backbone interfaced with lithium-niobate source and modulator units—are assembled and swapped to reconfigure the entire system, lowering cost and improving manufacturability for both research and industry.