The Nobel Prize in Physics 2018 was awarded “for groundbreaking
inventions in the field of laser physics" with one half to Arthur Ashkin “for the
optical tweezers and their application to biological systems", the other half
jointly to Gérard Mourou and Donna Strickland “for their method of generating
high-intensity, ultra-short optical pulses.”
Optical Tweezers, developed by Arthur Ashkin in 1987 use the radiation pressure of laser light to confine a microparticle , such as a virus, in three dimensions without any damage. It uses the "gradient force", proportional to the gradient of the intensity of the laser beam, to generate the three-dimensional potential well. This cannot only sense dynamics of microparticles but also apply controlled forces and torques without a physical touch.
Femtosecond laser pulses at high intensities have enabled controlled access to physical phenomena in the femto-, atto- and even zepto-second timescales. The femtosecond pulses enable extreme UV (EUV) light sources for lithography and fast ions for therapy. To generate high intensity short laser pulses, Strickland and Mourou invented a technique known as chirped pulse amplification (CPA). In order not to destroy the amplifying medium they stretched the laser pulses in time to reduce their peak power before amplifying them. Amplified pulses were then compressed in time to become shorter with extremely high peak powers. CPA’s uses include the millions of corrective eye surgeries that are conducted every year using the sharpest of laser beams.
The speakers will explain the physics and applications of these techniques to a general audience.