Petawatt laser "ready in June"

17 Jun 2002

The UK's Rutherford Appleton Laboratory inaugurates the petawatt upgrade to its Vulcan laser

Rutherford Appleton Laboratory in the UK will be home to the world's most intense laser by the end of June, officals at the lab say.

Once complete, the three-year project to upgrade the Vulcan laser facility will produce 500 fs pulses that have a peak power of over 1 petawatt and an intensity of 10 ²¹ W/cm². This will be the highest laser intensity ever produced.

The Vulcan laser is already capable of producing 100 terawatt pulses with one of its two existing beamlines, and these facilities will still be available to users following the upgrade.

Henry Hutchinson, director of the Central Laser Facility (CLF) that has built the upgrade, said of the new beam: "With the petawatt upgrade, scientists will have a unique opportunity to do physics at the frontiers of their subject."

Speaking at the inauguration of the petawatt facility, Mike Key, former chief of the CLF and now head of petawatt science at Lawrence Livermore National Laboratory, US, said: "The Vulcan laser is the best short-pulse, high-intensity facility in the world."

The new beamline uses chirped-pulse amplification to produce the petawatt pulses. The technique takes an ultrashort pulse emitted by a Nd:glass oscillator, stretches it to a few nanoseconds in length, and then amplifies it.

The amplified pulse is then re-compressed to a 500 fs duration using a pair of diffraction gratings. Finally, this compressed pulse is focused by a parabolic mirror to a 10 µm spot inside a new target area.

The pulse-compression stage is performed by two massive diffraction gratings, spaced 13 m apart. This takes place under a vacuum, as air would destroy the beam's wavefront. A new adaptive optics system maintains a high-quality beam profile.

Once the Vulcan petawatt is up and running, scientists will be able to perform experiments that mimic the conditions inside stars. A team from Imperial College, London, will be the first external users of the upgraded beam, with their experiments planned for November.

Author
Michael Hatcher is technology editor of Opto & Laser Europe magazine.