[1] Kolbas R M, Anderson N G, Laidig W D, Lo Y C, Hsieh KY and Yang Y J
1988 IEEE J. Quantum Electron. 24 1605

[2] Bour D P, Gilbrt D B, Fabian K B, Bednarz J P and Ettenberg M 1990
IEEE Photon. Technol. Lett. 2 173

[3] Reinberg A R, Riseberg L A, Brown R M, Wacker R W and Holton W C
1971
Appl. Phys. Lett. 19 11

[4] Lacovara P, Chol H K and Wang C A 1991 Opt. Lett.
16 1089

[5] Sugiyama A, Katsurayama M, Anzaib Y and Tsuboi T 2006 J.
Alloys Compd. 408--412 780

[6] DeLoach L D, Payne S A, Chase L L, Smith LK and Kway W L 1993
IEEE J. Quantum Electron. 29 1179

[7] Aron A, Aka G, Viana B and Kahn-Harari A 2001
Opt. Mater. 16 181

[8] Krupke W F and Chase L L 1990 Opt. Quantum Electron.
22 S1

[9] McCumber K E 1994 Phys. Rev. A 136 954

[10] Payne A A, Chase L L and Smith L K 1992 IEEE J. Quantum
Electron. 28 2619

[11] Wang P, Dawes J M and Dekker P 1999 J. Opt. Soc. Am. B
16 63

[12] Liao J S, Lin Y F and Chen Y J 2004 J. Crystal Growth
269 484