Smallest on-chip optical modulator has switching speed up to 11 Gbit/s
Electrical engineers at the University of Rochester (Rochester, NY) have taken a step towards reducing the size of photonic integrated circuits, by creating the smallest on-chip modulator yet.1 The device consistes of a thin film of lithium niobate (LN) bonded on a silicon dioxide layer to create a modulator that, besides being small, operates at high speed and is energy-efficient.
The lab of Qiang Lin, professor of electrical and computer engineering, used 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.
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 occupies an electro-optical modal volume of a mere 0.58 μm3 and has a modulation bandwidth of 17.5 GHz (allowing practical switching speeds of up to 11 Gbit/s) and a tuning efficiency of up to 1.98 GHz/V.
The modulator project builds upon the lab’s previous use of LN to create a photonic nanocavity. At only about a micron in size, the nanocavity can tune wavelengths using only two to three photons at room temperature, “the first time we know of that even two or three photons have been manipulated in this way at room temperatures,” Lin says. That device was described in a paper in Optica.2
Applications include communications, computing, and quantum photonic information processing.
REFERENCE:
1. Mingxiao Li et al., Nature Communications (2020); https://doi.org/10.1038/s41467-020-17950-7.
2. Mingxiao Li et al., Optica (2020); https://doi.org/10.1364/OPTICA.6.000860.
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.