Optomechanical measurement of the Abraham force in an adiabatic liquid-core optical-fiber waveguide

We report quantitative experimental measurements of the Abraham force associated with a propagating optical wave. We isolate this force using a guided light wave undergoing an adiabatic mode transformation along a liquid-filled hollow optical fiber (HOF). Utilizing this light intensity distribution within the liquid, we generate a time-averaged, nonvanishing Abraham force density, while simultaneously suppressing the Abraham-Minkowski force density. The incident laser field induces a linear axial displacement of the air-liquid interface inside the HOF, which provides a direct experimental measure of the Abraham force density. We find good agreement between the experimental results and theoretical determinations of the Abraham force density.