We’re thrilled that the 2018 Nobel Prize in Physics was awarded to three innovative scientists – Arthur Ashkin, Gérard Mourou, and Donna Strickland, the first woman to win the prize in 55 years.
The trio shared the prize for “groundbreaking inventions in the field of laser physics,” which included basic and applied research on femtosecond laser
Arthur Ashkin’s Optical Tweezers
Arthur Ashkin invented optical tweezers that grab particles, atoms, viruses and other living cells with their laser beam fingers. This new tool allowed Ashkin to use the radiation pressure of light to move physical objects. He succeeded in getting laser light to push small particles towards the center of the beam and to hold them there. Optical tweezers had been invented.
A major breakthrough came in 1987 when Ashkin used the tweezers to capture living bacteria without harming them. He immediately began studying biological systems and optical tweezers are now widely used to investigate the machinery of life.
Breaking the barrier with ultra-fast laser pulses
Gérard Mourou and Donna Strickland paved the way towards the shortest and most intense laser pulses ever created by mankind. Their revolutionary article was published in 1985 and was the foundation of Strickland’s doctoral thesis.
Their novel approach created ultrashort, high-intensity laser pulses without destroying the amplifying material. First, they stretched the laser pulses in time to reduce their peak power, then amplified them, and finally compressed them. If a pulse is compressed in time and becomes shorter, then more light is packed together in the same tiny space – the intensity of the pulse increases dramatically.
Strickland and Mourou’s newly invented technique, called chirped pulse amplification, CPA, soon became standard for subsequent high-intensity lasers. Its uses include the millions of corrective eye surgeries that are conducted every year using the sharpest of laser beams. Chemists already use CPA to study molecular systems on the femtosecond timescale.
Star Trek’s tractor beam becomes a reality
Arthur Ashkin had a dream: imagine if beams of light could be put to work and made to move objects. In Star Trek, the cult series that started in 1964, a tractor beam can be used to retrieve objects, even asteroids in space, without touching them. Of course, this sounds like pure science fiction. We can feel that sunbeams carry energy – we get hot in the sun – although the pressure from the beam is too small for us to feel even a tiny prod. But could its force be enough to push extremely tiny particles and atoms?
The innumerable areas of application for these discoveries have not yet been completely explored. However, even now these celebrated inventions allow us to rummage around in the microworld in the best spirit of Alfred Nobel – for the greatest benefit to humankind.
Download a scientific brief on the laser physics prize.
Sources: The Nobel Prize in Physics 2018. NobelPrize.org
Illustrations © Johan Janestad, the Royal Swedish Academy of Sciences”