Laser-sharp research sees three top boffins win the Nobel Prize in physics

First woman in 55 years and the oldest recipient to date

lasers

The 2018 Nobel Prize in Physics has been awarded to a trio of researchers for their work in developing powerful lasers.

Half of the prize money - worth nine million Swedish kronor ($1m or £770,000) - will go to Arthur Ashkin, a retired physicist who was the first to invent “optical tweezers” whilst working at Bell Labs. At 96, he is the oldest recipient of the prize to date.

Optical tweezers are fashioned from focused laser beams that can trap tiny particles inside. The motion of the light particles in the laser create pressure forces that can either keep the particles in place or nudge them elsewhere. They have been used to manipulate and study DNA, cells and viruses.

The rest of the cash will be split between Gérard Mourou, a retired physicist, and Donna Strickland, an associate professor at the University of Waterloo, Canada. They have been awarded "for their method of generating high-intensity, ultra-short optical pulses.” Strickland is only the third woman to have won the Nobel Prize in physics, the last prize was awarded to Maria Goeppert-Mayer, 55 years ago.

Mourou and Strickland’s technique, known as chirped pulse amplification, boosts the power of a laser pulse to petawatt (1015 W) levels. It was developed when they were both researchers at the University of Rochester and has been employed to create some of the most powerful lasers in laboratories worldwide.

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To achieve the effect a beam is reflected off mirrors and passed through a series of gratings to separate the waves travelling at lower frequencies from the ones at higher frequencies. The beam is said to be positively ‘chirped’ when the low frequencies lag behind the high frequencies, effectively stretching out the laser beam.

It is then passed to through a gain medium, a material that increases the amplitude of the laser waves by a million times or more, and then compressed. The ultrashort zaps only last for a femtosecond (10-15).

Chirped pulse amplification has been used to study the properties of light and its interactions with particles, as well as laser micromachining to carefully cut into materials for chips or even laser eye surgery. ®




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