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In situ tunable photonic filters and memories are important for emerging quantum and classical optics technologies. However, most photonic devices have fixed resonances and bandwidths determined at the time of fabrication. Here we present an in situ tunable optical resonator on thin-film lithium niobate. By leveraging the linear electro-optic effect, we demonstrate widely tunable control over resonator frequency and bandwidth on two different devices. We observe up to ∼50 × tuning in the bandwidth over ∼50 V with linear frequency control of ∼230 MHz/V. We also develop a closed-form model predicting the tuning behavior of the device. This paves the way for rapid phase and amplitude control over light transmitted through our device.

Second-order nonlinear optical processes convert light from one wavelength to another and generate quantum entanglement. Creating chip-scale devices to efficiently control these interactions greatly increases the reach of photonics. Existing silicon-based photonic circuits utilize the third-order optical nonlinearity, but an analogous integrated platform for second-order nonlinear optics remains an outstanding challenge. Here we demonstrate efficient frequency doubling and parametric oscillation with a threshold of tens of micro-watts in an integrated thin-film lithium niobate photonic circuit. We achieve degenerate and non-degenerate operation of the parametric oscillator at room temperature and tune its emission over one terahertz by varying the pump frequency by hundreds of megahertz. Finally, we observe cascaded second-order processes that result in parametric oscillation. These resonant second-order nonlinear circuits will form a crucial part of the emerging nonlinear and quantum photonics platforms.

Since the advent of the laser, acousto-optic modulators have been an important tool for controlling light. Recent advances in on-chip lithium niobate waveguide technology present new opportunities for these devices. We demonstrate a collinear acousto-optic modulator in a suspended film of lithium niobate employing a high-confinement, wavelength-scale waveguide. By strongly confining the optical and mechanical waves, this modulator improves a figure-of-merit that accounts for both acousto-optic and electro-mechanical efficiency by orders of magnitude. Our device demonstration marks a significant technological advance in acousto-optics that promises a novel class of compact and low-power frequency shifters, tunable filters, non-magnetic isolators, and beam deflectors.

Tuning and reconfiguring of nanophotonic components are needed to realize systems incorporating many components. The electrostatic force can deform a structure and tune its optical response. Despite the success of electrostatic actuators, they suffer from trade-offs between tuning voltage, tuning range, and on-chip area. Piezoelectric actuation could resolve these challenges, but only pm-per-volt scale wavelength tunability has been achieved. Here we propose and demonstrate compact piezoelectric actuators, called nanobenders, that transduce tens of nanometers per volt. By leveraging the non-uniform electric field from submicron electrodes, we generate bending of a piezoelectric nanobeam. Combined with a sliced photonic crystal cavity to sense displacement, we show tuning of an optical resonance by ~ 5 nm V⁻¹ (0.6 THz V⁻¹) and between 1520 ~ 1560 nm (~ 400 linewidths) within 4 V. Finally, we consider tunable nanophotonic components enabled by the nanobenders.