Modulated annular Bessel beams and their optical characteristics

Abstract

Motivated by the generation process of circular Airy beams (CABs), we propose two kinds of annular beams by modulating the Bessel functions, and such annular beams are called as modulated annular Bessel beams (MABBs) and truncated modulated annular Bessel beams (TMABBs). We have investigated their propagation and focusing characteristics through numerical simulations and experimental demonstrations. In free space, both MABBs and TMABBs exhibit autofocusing behaviors, forming focal spots with significantly suppressed sidelobes compared to Bessel beams. The position and intensity of the autofocusing peak are flexibly tunable by adjusting structural parameters such as the main ring radius and decay coefficient. In the focusing systems, both MABBs and TMABBs produce symmetric axial intensity distributions accompanied by pronounced high-frequency oscillations near the focal plane. The detail focusing properties can be manipulated by controlling the main ring radius and decay coefficient. Experimental results confirm the key trends predicted by simulation. Our result may expand the application potential of modulated Bessel beams in areas such as optical imaging, communications, and precision optical manipulation.