Caged Light
Light likes to keep on moving no matter what. But researchers have built an optical cage that can temporarily catch light and release it again, they report in the January issue of Nature Photonics. The development is an important step towards solid-state optical memory devices that may ultimately play a crucial role in ultra-fast optical communication networks or optical computers.Takasumi Tanabe and colleagues use a photonic crystal – a piece of silicon riddled with tiny holes – to create an optical cavity that can store light particles for more than a billionth of a second. This may not seem very long, but the beauty of these structures is in their size. Photonic crystals are man-made structures that can control the flow of light on the very smallest length scale possible – down to the wavelength of the waves. The team’s cavity is less than ten millionths of a metre long and made from silicon, which means that it could be integrated into miniature optical chips that can process light in the way microelectronics processes electrons.The temporary storage effect means that light travelling through the cage is effectively slowed down to a speed of just 5.8 km per second, 50,000 times slower than in a vacuum. This is the slowest speed ever measured in an insulator material.
Author contact:Takasumi Tanabe (NTT Basic Research Laboratories, Kanagawa, Japan)Tel: +81 46 240 4825; E-mail: takasumi@nttbrl.jp