Optical Tweezers comes of age: new studies in liquid, air and vacuum

Abstract: In science fiction, one is quite familiar with the idea of moving objects using laser beams, evoking concepts such as a “tractor beam”. In the laboratory, science fiction turns into science fact: a powerful technique known as “optical tweezers” (OT) shows that micrometre-sized particles (and even biological material and atoms) can be grabbed, moved and generally manipulated without any physical contact using optical forces. This is a powerful demonstration of the optical dipole or gradient force in action and this approach was recognized in the Nobel Prize in Physics in 2018. Such “optical tweezers”, based primarily on Newton’s laws and fundamental optics have enabled unprecedented insight about biological molecules such as DNA and molecular motors. In the microscopic world of optical tweezers, researchers are now harnessing these systems to study a host of science.

This talk will give a perspective of emergent studies in manipulation with emphasis for fundamental studies. This includes the use of particles with specific material properties. This can include the rotation of particles in liquid and vacuum using vaterite [1] and nanovaterite particles [2]. These particles exhibit a birefringence that allows them to spin when using circularly polarised trapping beams. Such studies can lead to very high rotation rates. This work may be extended to study the binding of particles in vacuum [3]. Separately the use of up-converting particles is very intriguing and can lead to new understanding of temperature for internal degrees of freedom and centre-of-mass motion [4].