Evanescent Bessel beams

Bessel beams of the evanescent kind are presented and analyzed. They rapidly decay with propagation but retain their original transversal shape. A physical method of generation is proposed in the form of propagation of an ordinary (nonevanescent) Bessel beam across an interface between two different dielectric media. Transmission and reflection coefficients are calculated for this type of beam. The analysis is vectorial and is fully consistent with Maxwell’s equations. Apodized beams of Gauss–Bessel and Circ–Bessel types are propagated by numerical simulation and are shown also to retain a narrow central lobe. Beams of these types have evident advantages in near-field applications, microscopy, and high-density data storage with subwavelength resolution.