The award was announced today and went to three people: Arthur Ashkin (b. 1922) at Bell Laboratories in New Jersey, Gérard Mourou (b. 1944) at École Polytechnique in France, and Donna Strickland (b. 1959) at the University of Waterloo in Canada. The press release announcing the winners provides concise descriptions of the work for which they were recognized.
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 realise an old dream of science fiction – using the radiation pressure of light to move physical objects. He succeeded in getting laser light to push small particles towards the centre 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.
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.
Using an ingenious approach, they succeeded in creating 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.
The innumerable areas of application 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.
There are a couple of interesting things about this year’s winners. Much attention has been given to the fact that Strickland is only the third woman to have received the Nobel prize, after Marie Curie in 1903 and Maria Goeppert Mayer in 1963. But what also struck me is that Strickland has only reached the rank of associate professor at her university and not the top rank of professor. This will be a source of embarrassment at her institution that they were not able to recognize her merits.
Strickland got her PhD from the physics department of the University of Rochester in 1989. I was a postdoctoral fellow there during the period 1986-1988. But my area of theoretical nuclear physics did not overlap with her area of experimental physical optics so I do not recall her, though I am sure we must have crossed paths during that time. Since the department was not that large.
Another interesting tidbit is that Ashkin is 96 years old and the oldest to receive the prize. Since the prize is only given to living scientists, he did not have many years of eligibility left, though he is apparently still active in research.