[1] E. Esarey, P. Sprangle, M. Pilloff et al.. Theory and group velocity of ultrashort, tightly focused laser pulses. J. Opt. Soc. Am. B, 1995, 12(9)∶ 1695
[3] J. Durnin, J. J. Miceli, J. H. Eberly. Diffraction-free beams. Phys. Rev. Lett., 1987, 58(19)∶ 1499
[4] J. Durnin. Exact solutions for nondiffracting beams I. The scalar theory. J. Opt. Soc. Am. A, 1987, 4(4)∶ 651