Observation of microscale nonparaxial optical bottle beams

We predict and experimentally observe three-dimensional microscale nonparaxial optical bottle beams based on the generation of a caustic surface under revolution. Such bottle beams exhibit high contrast between the surrounding surface and the effectively void interior. Via caustic engineering, we can precisely control the functional form of the high-intensity surface to achieve microscale bottle beams with longitudinal and transverse dimensions of the same order of magnitude. Although, in general, the phase profile at the input plane can be computed numerically, we find closed-form expressions for bottle beams with various types of surfaces both in the real and in the Fourier space.