[1] J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1962).

[2] R. A. Beth, Phys. Rev. 50, 115 (1936).

[3] L. Allen, M. W. Beijersbergen, and R. J. C. Spreeuw, Phys. Rev. A 45, 8185 (1992).

[4] H. He, M. E. J. Friese, N. R. Heckenberg, and H. Rubinsztein-Dunlop, Phys. Rev. Lett. 75, 826 (1995).

[5] M. E. J. Friese, J. Enger, H. Rubinsztein-Dunlop, and N. R. Heckenberg, Phys. Rev. A 54, 1593 (1996).

[6] T. Kuga, Y. Torii, N. Shiokawa, T. Hirano, Y. Shimizu, and H. Sasada, Phys. Rev. Lett. 78, 4713 (1997).

[7] B. Xia and W. Hai, Chin. Opt. Lett. 3, 373 (2005).

[8] M. P. MacDonald, G. C. Spalding, and K. Dholakia, Nature 426, 421 (2003).

[9] J. Leach, M. J. Padgett, S. M. Barnett, S. Franke-Arnold, and J. Courtial, Phys. Rev. Lett. 88, 257901 (2002).

[10] J. Leach, J. Courtial, K. Skeldon, S. M. Barnett, S. Franke-Arnold, and M. J. Padgett, Phys. Rev. Lett. 92, 013601 (2004).

[11] A. T. Friberg, E. Tervonen, and J. Turunen, J. Opt. Soc. Am. A 11, 1818 (1994).

[12] A. Friberg, C. Gao, B. Eppich, and H. Weber, Proc. SPIE 3110, 317 (1997).

[13] N. Hodgson and H. Weber, Optical Resonators: Fundamentals, Advanced Concepts and Applications (Springer Verlag, Berlin, 1997).

[14] A. E. Siegman, Laser (University Science Books, Mill Valley, 1986).

[15] E. Abramochkin and V. Volostnikov, Opt. Commun. 83, 123 (1991).

[16] D. C. Hanna, IEEE J. Quantum Electron. 5, 483 (1969).

[17] C. Tamm and C. O. Weiss, J. Opt. Soc. Am. B 7, 1034 (1990).

[18] H. Laabs and B. Ozygus, Opt. Laser Technol. 28, 213 (1996).