Meaning of phase in subwavelength elastic scattering

Abstract

Phase is a common wave parameter used to describe the consequences of light–matter interaction. When the scattering center is smaller than the wavelength, a simplistic geometric interpretation of the measured phase is insufficient. Using energetic arguments, we show that the appropriate description of measurements performed far away from subwavelength objects involves the duration and the effective volume of the elastic scattering event. Because the evanescent fields contribute significantly to coupling and releasing of energy, the effective interaction volume is significantly larger than the physical size of subwavelength particles. Our results also provide means to describe scattering phenomena in dense media where scatterers are in close proximity to each other.