History of Optical Trapping and Manipulation of Small Neutral Particles, Atoms, and Molecules

Abstract

I was asked by Prof. Rigler to help introduce this conference on single molecule spectroscopy by reviewing the history of optical trapping and manipulation of small neutral particles. Laser trapping techniques play a major role in single particle studies in physics, chemistry, and biology. The unique capabilities of these techniques have had a revolutionary impact in various subfields of these same sciences where single particles play a role. In the field of light scattering, it has led to the highest-resolution studies of Mie scattering, the first high-resolution observations of the resonant behavior of macroscopic spherical particles, and the use of these resonances in many applications in linear and nonlinear optics and lasers. The highest-Q optical resonances ever observed have been found in these so-called Mie resonance or “whispering gallery modes.” In atomic physics, laser trapping and cooling techniques have led to the optical trapping of individual atoms, to atom cooling down to the lowest kinetic temperatures in the universe, to Bose—Einstein Condensation, and, more recently, to atom lasers. Practical advances in atomic clocks and measurement of gravitational forces have also been made. In the biological sciences and chemistry, use of laser techniques has led to the trapping and manipulation of single living cells, organelles within cells, single biological molecules, and measurement of the mechanical forces and elastic properties of cells and molecules.