AsianScientist (Jul. 1, 2015) – Researchers have developed a three dimensional (3D) gap-plasmon antenna which can focus light into a space a few nanometers wide. Their findings were published in Nano Letters.
Focusing light into a point-like space is an active research field with many applications. However, concentrating light into a smaller space than its wavelength is often hindered by diffraction. To tackle this problem, many researchers have utilized the plasmonic phenomenon of a metal where light can be confined to a greater extent by overcoming the diffraction limit.
In particular, many efforts have focused on developing a two dimensional (2D) plasmon antenna and were able to focus light to an area under five nanometers wide. However, this 2D antenna revealed a challenge: the light disperses to the opposite end regardless of how small its beam was focused. To resolve this issue, a 3D structure had to be employed to maximize the light’s intensity.
Adopting the proximal focused-ion-beam milling technology, a team led by Professors Kim Myung-Ki and Lee Yong-Hee from the Physics Department at the Korea Advanced Institute of Science and Technology (KAIST) developed a 3D gap-plasmon antenna.
By squeezing the photons into a 3D nano space of 4 x 10 x 10 nm3 size, the researchers were able to increase the intensity of light to 400,000 times stronger than that of the incident light. Capitalizing on the enhanced intensity of light within the antenna, they intensified the second-harmonic signal and verified that the light was focused in the nano gap by scanning cathodoluminescent images.
The researchers anticipate that this technology will improve the speed of data transfer and processing up to the level of a terahertz (one trillion times per second) and to enlarge the storage volume per unit area on hard disks by 100 times.
In addition, high definition images of submolecule size can be taken with actual light, instead of with an electron microscope, while improving the semiconductor process to a smaller size of few nanometers.
“A simple yet ingenious idea has shifted the research paradigm from 2D gap-plasmon antennas to 3D antennas. This technology will see numerous applications including in the field of information technology, data storage, imaging medical science, and semiconductor processes,” said Kim.
The article can be found at: Kim et al. (2015) Squeezing Photons into a Point-Like Space.
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Source: KAIST.
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