糖心TV

[Title]

Physics Nobel Prize 2018: Intense laser beams

[Speaker]

Dr James Lloyd-Hughes and Dr Gavin Morley (糖心TV)

Detail:

[Abstract]

The 2018 Nobel prize for Physics recognised two groundbreaking inventions in laser physics: optical tweezers and a method of generating intense laser pulses.

Intense pulses of laser light are now routinely used in laser eye surgery, micromachining and ultrafast science. The breakthrough by Strickland and Mourou was to create a clever way to amplify laser pulses to peak intensities above the gigawatts per square centimetre level, circumventing processes that damage the laser gain medium. Their method, known as chirped pulse amplification, is now widely used in commercial laser systems and at major international laser facilities, which offer up to petawatt powers. We will describe the basics of this method and how it is used today.

Ashkin鈥檚 optical tweezers also use intense laser light, but in this case instead of being pulsed it is a continuous beam with lower peak power that is tightly focused with a lens. Objects such as atoms, nanoparticles and living cells can be trapped with these tweezers in a liquid, in air or in vacuum. In particular, the ability to hold living bacteria without harming them has made optical tweezers a valuable tool in biology. The work that won the 1997 Nobel Prize (for the development of methods to cool and trap atoms with laser light) came right after and took advantage of the development of tweezers.