[1] H. Po, J. D. Cao, and B. M. Laliberte, Electron. Lett. 29, 1500 (1993).
[2] G. Mitchaard and R. Waarts, Laser Focus World 35 (1), 113 (1999).
[3] V. Dominic, S. MacCormaack, R.Waarts, and S. Sanders, Electron. Lett. 35, 1158 (1999).
[4] I. Bennion, J. A. R. Williams, L. Zhing, and K. Sugden, Opt. and Quantum Electron. 28, 93 (1996).
[5] D. Marcuse, IEEE J. Quantum Electron. 29, 2390 (1993).