All-dielectric nanoresonators could be useful as augmenters for photodetectors or as passive IR coolers.
University of Wisconsin-Madison engineers and their colleagues at Fudan University (Shanghai,China) have created a nanoscale device that has the optical cross-section of an object 10,000 times its size. They showed how a single nanoresonator can manipulate light to make itself appear very large as both an absorber and an emitter.
The researchers created an optical nanoresonator in which the wavelength of light is much larger than in a vacuum; the device can gather light and scatter it over a very large area, harnessing its output for imaging applications that make microscopic particles appear large.
"We are developing photodetectors based on this technology and, for example, it could be helpful for photographers wanting to shoot better quality pictures in weak light conditions," says Zongfu Yu, one of the University of Wisconsin researchers.
Passive cooling with sky as heat sink
Given the nanoresonator's capacity to absorb large amounts of light energy, the technology also has potential in applications that harvest the sun's energy with high efficiency. In addition, Yu envisions simply allowing the resonator emit that energy in the form of IR radiation toward the sky, which is very cold. Because the nanoresonator has a large optical cross-section it can shed a lot of heat energy, making for an efficient passive cooling system.
The simple dielectric structures are compatible with existing optical integrated circuit technology.
Theresearch is supported by the Office of Naval Research and the Wisconsin Alumni Research Foundation (WARF).
1. Ming Zhou et al., Physical Review Letters (2015); http://dx.doi.org/10.1103/PhysRevLett.115.023903