Optical resonances in microsphere photonic nanojets

We report microsphere photonic nanojets, using the Mie theory to analyse the behaviour of the Poynting vector fields for incident visible wavelengths. Optical field structures of optical whirlpools and rhombuses are observed when incident plane waves transmit through 5 μm and 30 μm dielectric microspheres of various refractive indices from n = 1.4 to 2.2 embedded in vacuum and water media. The waist of the photonic nanojets and the distance between the microsphere and the position of maximum electric intensity determines the potential for super-resolution imaging. These parameters vary with the refractive index and size of the dielectric microspheres. We have shown that the waists of the photonic nanojets are beyond the diffraction limit without significant optical diffraction. (paper)