Shanghai lab pushes limits of laser power

Method used to modify atoms promises new materials for wide array of products

The greatest peak-power laser pulse ever measured was recorded in a Shanghai lab in August, as Chinese scientists move closer to transforming the internal structure of atoms by using concentrated energy to cut them up.

Structural transformations promise to bring about the invention of new materials in areas such as aviation, aerospace, high-speed rail, cancer treatment, smartphones and dark matter.

Long Yuxin, director of the State Key Laboratory of High Field Laser Physics at the Shanghai Institute of Optics and Fine Mechanics under the Chinese Academy of Sciences, said about 10 labs worldwide have been dedicated to obtaining intense laser pulses, one of the frontier science sectors of the 21st century. The early August achievement is a milestone for the Shanghai lab, which obtained a laser pulse output with a peak wattage of 5.3 times 10 to the 15th power.

Liang Xiaoyan, a leading researcher at the lab, said the stronger and faster a laser is, the more able it is to remodel the structure of an atom or to drag out some of its electrons and protons.

"Laser-based proton knives are quite promising for cancer treatment," Liang said. "A laser-based medical device will have several advantages, such as being more compact, with easier radiation shielding and perhaps cheaper maintenance, compared with current state-of-the-art proton therapy facilities."

"When the structure of atoms is changed, special materials can be created according to various requirements for different industrial and social sectors," she added.

Ultrafast lasers may also make faster smartphones.

"Currently the speed of the state-of-the-art processors, such as those in the newest mobile phones, is several GHZ and is already very close to the actual processor speed limit. But if we can control the electrical and optical properties... hopefully we'll see fairly impressive advancement in the running speed of smart-phones," said Li Ruxin, direct-or of the lab.

The laser power achievement was the result of a new solution to a key problem that has puzzled their international fellows.

Some crystal devices are used to amplify an input pulse, which become less efficient after passing through the crystal, especially when the crystal gets larger and "parasitic" action rises in the crystal and degrades output, Liang said. The scientists found a way to suppress such emissions.

The researchers believe the laser facility, one of the key projects in Shanghai's mission to become a science and technology center with global influence, will become the first in the world to obtain laser pulse output wattage of 10 to the power of 16 in 2017.

zhouwenting@chinadaily.com.cn

(China Daily 09/09/2016 page5)