Light Slowed, Trapped, Released at Will in New Way

Tinkering with the design has resulted in what Dionne and Lawrence describe as an important platform technology with numerous practical applications.

The devices demonstrated so-called quality factors up to 2,500, which is two orders of magnitude (or 100 times) higher than any similar devices have previously achieved. Quality factors are a measure describing resonance behavior, which in this case is proportional to the lifetime of the light. “By achieving quality factors in the thousands, we’re already in a nice sweet spot from some very exciting technological applications,” said Dionne.

For example, biosensing. A single biomolecule is so small that it is essentially invisible. But passing light over a molecule hundreds or thousands of times can greatly increase the chance of creating a detectable scattering effect.

Dionne’s lab is working on applying this technique to detecting COVID-19 antigens – molecules that trigger an immune response – and antibodies – proteins produced by the immune system in response. “Our technology would give an optical readout like the doctors and clinicians are used to seeing,” said Dionne. “But we have the opportunity to detect a single virus or very low concentrations of a multitude of antibodies owing to the strong light-molecule interactions.” The design of the high-Q nanoresonators also allows each antenna to operate independently to detect different types of antibodies simultaneously.

Though the pandemic spurred her interest in viral detection, Dionne is also excited about other applications, such as LIDAR – or Light Detection and Ranging, which is laser-based distance measuring technology often used in self-driving vehicles – that this new technology could contribute to. “A few years ago I couldn’t have imagined the immense application spaces that this work would touch upon,” said Dionne. “For me, this project has reinforced the importance of fundamental research – you can’t always predict where fundamental science is going to go or what it’s going to lead to, but it can provide critical solutions for future challenges.”

This innovation could also be useful in quantum science. For example, splitting photons to create entangled photons that remain connected on a quantum level even when far apart would typically require large tabletop optical experiments with big expensive precisely polished crystals. “If we can do that, but use our nanostructures to control and shape that entangled light, maybe one day we will have an entanglement generator that you can hold in your hand,” Lawrence said. “With our results, we are excited to look at the new science that’s achievable now, but also trying to push the limits of what’s possible.”

Additional Stanford co-authors include graduate students David Russell Barton III and Jefferson Dixon, research associate Jung-Hwan Song, former research scientist Jorik van de Groep, and Mark Brongersma, professor of materials science and engineering. This work was funded by the DOE-EFRC, “Photonics at Thermodynamic Limits” as well as by the AFOSR. Jen is also an associate professor, by courtesy, of radiology and a member of the Wu Tsai Neurosciences Institute and Bio-X.