The far properties of nonparaxial cosine-squared Gaussian beams

摘要

Based on the Rayleigh-Sommerfeld diffraction integrals, the closed-form expression of nonparaxial cosine-squared Gaussian beams in free space is derived. The power in the bucket (PIB) of nonparaxial regime is introduced to characterize the beam quality of nonparaxial beams in the far field. It is found that the intensity and PIB of nonparaxial cosine-squared Gaussian beams depends on f parameter, decentered parameter, and the PIB is additionally depends on the bucket's size taken. For a given bucket's size, the smaller decentered parameter and f parameter result in the better power focusability in the far field and the better beam quality.