Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

But the most exciting potential application for exawatt lasers is in fusion power plants that rely on a process called fast ignition. In the early stages, the National Ignition Facility will use petawatt lasers to compress a pellet of gold fuel until it heats up to 100 million °C, triggering fusion. Also at the conference this week, researchers from the facility reported that they’ve completed another step along the way to controlled fusion reactions, describing preliminary tests of their system using a 500,000-joule pulse to implode a fusion fuel pellet.

Fast ignition works differently. Instead of a single pulse, the technique would use lower-power lasers to “compress the fuel without worrying about heating it, and then a short-pulse [exawatt] laser that acts as a spark plug,” igniting the fusion reaction, says Ditmire.

“Whether this will work is controversial,” Ditmire admits. Aiming such a short pulse might be problematic. In theory, though, the fast-ignition process should take less energy to operate. The most important measure of the performance of a fusion reactor is its gain, or the ratio of the energy required to operate the lasers to the amount of energy produced by the reaction. The Livermore facility’s goal is a gain of 15 to 20. “You need a gain of 100 to make a fusion power plant, and calculations show that exawatt lasers could get it,” says Ditmire.

But the new glass material isn’t the only key to building an exawatt laser. Ditmire’s group has also had success with new amplification techniques for making very short-duration pulses using the university’s Texas Petawatt Laser. According to Ditmire, the trick to making very high power is a technique called chirping, in which different frequencies of light are separated, run through glass amplifiers, and then run through a compressor to put them back together into a single, higher-power pulse. The Texas group’s method combines different types of glass amplifiers for this process, allowing for more compression of the light and therefore increasing the power output further. At the meeting, Ditmire reported using this technique to create 100-femtosecond pulses.

Ditmire isn’t the only researcher pushing for the development of exawatt lasers. The inventor of chirping, Gérard Mourou of the Ecole Polytechnique in France, is spearheading a European exawatt laser project called ELI, or Extreme Light Infrastructure. The European group plans to use titanium sapphire amplifiers instead of conventional glass.

1 comment. Share your thoughts »

Credit: Texas Petawatt Laser Project

Tagged: Energy, Materials, lasers, optics, light, fusion, materials science, cancer therapy

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me