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Hamamatsu Corp. - Earth Innovations LB 2/24

All-Metal Detector has Ultranarrow Absorption Band

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EVANSTON, Ill., Oct. 2, 2014 — A new all-metal photodetector with an ultranarrow absorption band could lead to biosensors with greater sensitivity than ever.

The device achieved a bandwidth of 12 nm by exploiting plasmonic surface lattice resonances of nanowire and nanoring arrays on optically thick, reflective metallic films.

“It's been a challenge to sense very small particles or very low concentrations of a substance,” said Northwestern University professor Dr. Koray Aydin, one of the developers. “The beauty of our design is that we found a way to engineer the material by using a different substrate.”

Typical absorber designs use two metal sheets with a nonmetallic insulating material in between. Aydin's team found that removing the insulating layer and leaving only metallic nanostructures caused the structure to absorb a much narrower band of light.

In the new device, light absorption reaches 90 percent at visible frequencies. The resonance absorption wavelength, amplitude of the absorption peak and the bandwidth can be tuned by altering the periodicity and thickness of arrays.

In addition to biosensors, Aydin said the design could also be used for applications in photothermal therapy, thermophotovoltaics, heat-assisted magnetic recording, thermal emission and solar steam generation.

The research was published in ACS Nano (doi: 10.1021/nn502617t).

For more information, visit www.northwestern.edu.
Cognex Corp. - Smart Sensor 3-24 GIF MR

Published: October 2014
Glossary
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
plasmonics
Plasmonics is a field of science and technology that focuses on the interaction between electromagnetic radiation and free electrons in a metal or semiconductor at the nanoscale. Specifically, plasmonics deals with the collective oscillations of these free electrons, known as surface plasmons, which can confine and manipulate light on the nanometer scale. Surface plasmons are formed when incident photons couple with the conduction electrons at the interface between a metal or semiconductor...
AmericasBiophotonicsIllinoisKoray AydinnanoNorthwestern UniversityplasmonicsResearch & TechnologySensors & Detectors

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