J. Eur. Opt. Society-Rapid Publ. 21, 35( 2025) 49
Figure
3. Annular slits with radial grating information for different parameters.
Figure
4. Experimental graph of nondiffracting radial carpet-lattice beams with the same parameters as in Figure 1.
Figure 5. Recorded graphs of nondiffracting radial carpet-lattice beams for parameter m = 9 at different propagation distances after the lens:( a) z = 50 cm;( b) z = 80 cm;( c) z = 110 cm;( d) z = 140 cm;( e) z = 170 cm.
The nondiffracting beams are theoretical pattern instead of a physically realizable entity since they are characterized as carrying infinite energy and having an infinite extent. However, any actual physical beam is limited by the finite aperture of optical systems( such as the size of spatial light modulators, the radial range of gratings, etc.). Therefore, the radial carpet-lattice beam generated in experiments is essentially a pseudo-nondiffracting approximation, with a finite lattice depth and a truncated spectral distribution, and its nondiffracting characteristics are only valid within a finite propagation distance.
Nevertheless, the beam can still exhibit a highly stable periodic intensity distribution within the preset propagation range, providing a feasible approximate solution for applications such as optical manipulation and particle trapping. On the basis of the experimental parameter, the maximum nondiffraction distance is obtained from the formula z max = R / tanh, wheretanh d / 2f, R is the finite output aperture, d is the annular slit with a diameter of 10 mm, here, f refers to the focal distance of the Fourier lens [ 5 ]. Therefore, we calculate the ideal maximum transmission distance as 400 cm.