Applicability of the soft and hard apodization techniques to suppress Bessel beam intensity oscillations

Abstract We investigate the applicability of the soft and hard apodization techniques to suppress Bessel beam intensity oscillations through varying several parametric quantities, which include the input pixel pitch, the quantized amplitude gray level number, the transverse wave vector, the incident wavelength and the amplitude smoothing parameter. The Bessel beam propagating intensities are simulated by the complete Rayleigh–Sommerfeld method. Three performance indicators are defined to characterize the stable propagation property of the diffracted Bessel beam, i.e., the longitudinal range with stable axial intensity, the axial intensity percentage deviation and the transverse intensity percentage deviation. Numerical results demonstrate that the intensity oscillations are substantially suppressed by the two apodization techniques within a wide range of parameters, and thus the apodized Bessel beams propagate stably during the whole propagation distance. Numerical simulation also reveals that the apodized Bessel beams process a good self-healing property when encountering a circular obstacle. In addition, the hard apodization technique shows obvious superiority to the soft apodization technique with 256 gray levels, such as a higher accuracy, a lower cost and an easier fabrication process.