Harnessing the Powers of Light to Power Computers

Light is said to be the source of life, and in the near future it may also form the basis of our daily personal computing needs. Recently, researchers at the University of Tsukuba harnessed specific light energies from a “packet” of light by creating a nanocavity, which could aid in the development of future all-optical computers.

Fiber optic cables already take advantage of the incredibly fast speed of light to transmit Internet data. However, these signals must first be converted into electrical impulses in the circuitry of your computer or smart TV before you can watch your favorite streaming show. Researchers are working on the development of new all-optical computers capable of performing calculations using light pulses. However, it is often difficult to precisely control the bursts of light energy, and new devices are needed to shape the light pulses in a switchable way.

In a study published last month in Nanophotonics, researchers at the University of Tsukuba tested a new metal waveguide containing a tiny nanocavity just 100 nanometers long. The size of the nanocavity is specially designed so that only specific wavelengths of light can enter it. This makes the nanocavity act almost like an artificial atom with tunable properties. As a result, light waves with corresponding resonant energy are transmitted, while other wavelengths are blocked. This has the effect of reshaping the light wave packet.

The team used light waves that travel along the interface of metal and air, called “surface plasmon polaritons”. This involves coupling the movement of the light wave through the air with the movement of electrons in the metal directly below. “You can imagine a surface plasmon polariton like what happens when a strong wind blows across the ocean. Water waves and air waves travel in concert,” says lead author Prof. Atsushi Kubo .

The waveguide was fabricated using a dye whose fluorescence properties changed depending on the presence of light energy. The team used light signals as short as 10 femtoseconds (i.e. 10 quadrillionths of a second) and created a “movie” of the resulting waves using resolution-resolved two-photon fluorescent microscopy. time. They discovered that only the spectral component corresponding to the resonance energy of the nanocavity could continue to propagate along the metal surface. “The ability to selectively reshape waveforms will be key to the development of future optical computers,” says Professor Kubo. The results of this project could also help streamline the design of other ultrafast optical spectroscopy devices.


This work was supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project, (JPMXP09F-17-NM-0068), JSPS KAKENHI (JP14459290, JP16823280, JP18967972, JP20J21825), JST N. Ichiji et al. : Femtosecond space warping imaging of SPP wave packet 11 CREST (JPMJCR14F1) and MEXT Q-LEAP ATTO (JPMXS0118068681), Japan. This study was supported by the National Institute of Materials Science Nanofabrication Platform and the University of Tsukuba.

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