Focusing property simulation of tapered-cladding single-mode hemispherical fiber micro-lenses

The properties of tapered-cladding single-mode hemispherical fiber micro-lenses whose radius is larger than twice of the core radius of the fiber are investigated by Monte Carlo simulation. The radial field distribution of the fiber is expressed as a Gaussian distribution. Simulation results show that the least confusion spots and the maximum axial intensity spots are not located at the focal plane of the hemispherical micro-lenses. The influence of the spherical aberration of the lenses on the spot size can not be neglected for micro-lenses with small curvature radius, and the Gaussian beam model typically used in the calculation of fiber micro-lenses is valid only when the radius of the refractive surface is larger than triple of the fiber core radius.