[1] R. L. Fork, C. H. Brito Cruz, P. C. Becher, and C. B. Shank, Opt. Lett. 12, 483 (1987).

[2] A. M. Weiner, J. P. Heritage, and E. M. Kirschner, J. Opt. Soc. Am. B 5, 1563 (1988).

[3] D. Yelin, D. Meshulach, and Y. Silberberg, Opt. Lett. 22, 1793 (1997).

[4] A. F. Verluise, V. Laude, Z. Cheng, C. Spielmann, and P. Tournois, Opt. Lett. 25, 575 (2000).

[5] E. Zeek, K. Maginnis, S. Backus, U. Russek, M. Murnane, G. Mourou, H. Kapteyn, and G. Vdovin, Opt. Lett. 24, 493 (1999).

[6] L. Zhu, P. Sun, D. Bartsch, W. R. Freeman, and Y. Fainman, App. Opt. 38, 168 (1999).

[7] C. Iaconis and I. A. Walmsley, IEEE J. Quantum Electron. 35, 501 (1999).