The electro-optical modulator takes advantage of lithium niobate, a “workhorse” material used by researchers to create advanced photonics integrated circuits. (Image: University of Rochester, illustration by Michael Osadciw)

Photonic integrated circuits that use light instead of electricity for computing and signal processing promise greater speed, increased bandwidth, and greater energy efficiency than traditional circuits using electricity. But they’re not yet small enough to compete in computing and other applications where electric circuits continue to reign.

Electrical engineers addressed the problem by using a material widely adopted by photonics researchers to create a miniature electro-optical modulator. The modulator is a key component of a photonics-based chip, controlling how light moves through its circuits.

The team used a thin film of lithium niobate (LN) bonded on a silicon dioxide layer to create a LN modulator that operates at high speed and is energy efficient. The method could be the foundation of large-scale LN photonic integrated circuits for applications in data communication, microwave photonics, and quantum photonics.

Lithium niobate has outstanding electro-optic and nonlinear optic properties but current LN photonic devices, made upon either bulk crystal or thin-film platform, require large dimensions and are difficult to scale down in size, which limits the modulation efficiency, energy consumption, and the degree of circuit integration. A major challenge lies in making high-quality nanoscopic photonic structures with high precision.

The modulator project builds upon the lab’s previous use of lithium niobate to create a photonic nanocavity — another key component in photonic chips. At only about a micron in size, the nanocavity can tune wavelengths using only two to three photons at room temperature. The modulator could be used in conjunction with a nanocavity in creating a photonic chip at the nanoscale.

For more information, contact Bob Marcotte at This email address is being protected from spambots. You need JavaScript enabled to view it..