New Breakthrough In Miniaturizing Light-Based Chips

A team of electrical engineers at the University of Rochester believe they’ve taken a major step in miniaturizing light-based chips. The team has created the smallest electro-optical modulator ever, using a widely adopted material by photonic researchers.

What is an electro-optical modulator?
This modulator is an optical device that is the key component of a photonics-based chip, controlling how light moves through its circuits.

The Problem
As you might know, that light-based 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 the problem here is that they’re not yet small enough to compete in computing and other applications where electric circuits continue to reign.

According to the recent paper published in Nature Communications, the lab of Qiang Lin, professor of electrical and computer engineering, describes using a thin film of lithium niobate (LN) bonded on a silicon dioxide layer to create not only the smallest LN modulator yet but also one that operates at high speed and is energy efficient.

“This paves a crucial foundation for realizing large-scale LN photonic integrated circuits that are of immense importance for broad applications in data communication, microwave photonics, and quantum photonics,” writes lead author Mingxiao Li, a graduate student in Lin’s lab.

Because of its outstanding electro-optic and nonlinear optic properties, lithium niobate has “become a workhorse material system for photonics research and development,” Lin says. “However, 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 is built on the lab’s previous use of lithium niobate to create a photonic nanocavity, another key component in photonic chips. The modulator could be used in conjunction with a nanocavity in creating a photonic chip at the nanoscale.

Journal Reference:
Mingxiao Li, Jingwei Ling, Yang He, Usman A. Javid, Shixin Xue, Qiang Lin. Lithium niobate photonic-crystal electro-optic modulator. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-17950-7