[1] V. S. Letokhov, Sov. Phys. JETP 26, 835 (1968).

[2] N. M. Lawandy, R. M. Salachandran, A. S. L. Gomes, and E. Sauvain, Nature 368, 436 (1994).

[3] D. S. Wiersma and A. Lagendijk, Phys. Rev. E 54, 4256 (1996).

[4] H. Cao, Y. G. Zhao, H. C. Ong, S. T. Ho, J. Y. Dai, J. Y. Wu, and R. P. H. Chang, Appl. Phys. Lett. 73, 3656 (1998).

[5] H. Cao, Y. G. Zhao, S. T. Ho, E. W. Seelig, Q. H. Wang, and R. P. H. Chang, Phys. Rev. Lett. 82, 2278 (1999).

[6] H. Cao, Y. G. Zhao, H. C. Ong, and R. P. H. Chang, Phys. Rev. B 59, 15107 (1999).

[7] H. Cao, J. Y. Xu, E. W. Seeling, and R. P. H. Chang, Appl. Phys. Lett. 76, 2997 (2000).

[8] H. Cao, J. Y. Xu, D. Z. Hang, S. H. Chang, S. T. Ho, E. W. Seelig, X. Liu, and R. P. H. Chang, Phys. Rev. Lett. 84, 5584 (2000).

[9] H. Cao, Y. Ling, J. Y. Xu, and C. Q. Cao, and P. Kumar, Phys. Rev. Lett. 86, 4524 (2001).

[10] H. Wang, Z. Ouyang, Y. Han, Q. Meng, Y. Jian, and X. Luo, Acta Opt. Sin. (in Chinese) 26, 1691 (2006).

[11] H. Wang, Z. Ouyang, Y. Han, Y. Zhong, and S. Ruan, Acta Opt. Sin. (in Chinese) 27, 1295 (2007).

[12] Q. Liu, Chinese J. Lasers (in Chinese) 34, 777 (2007).

[13] D. Wiersma, Nature 406, 132 (2000).

[14] Y. Xie and Z. Liu, Phys. Lett. A 341, 339 (2005).

[15] Y. M. Xie and Z. D. Liu, Chin. Phys. Lett. 22, 2827 (2005).

[16] M. Born and E. Wolf, Principles of Optics (7th edn.) (Cambridge University Press, London, 1999) Chapter 1.6.