[1] [1] -4): 355.

          Tang Z K, Ping Yu, Wong G K L, et al. Nonlinear Optics, 1997, 18(2

[2] [2] Tang Z K, Wong G K L ,Yu P, et al. Appl. Phys. Lett., 1998, 72(25):

          3270.

[3] [3] Bagnall D M, Chen Y F. Applied Physics Letters, 1997, 70(17): 2230.

[4] [4] Bagnall D M, Chen Y F, et al. Cryst. Growth, 1998, 184(2): 605.

[5] [5] Vanhensden K, Seager C H, Warren W L, et al. Appl. Phys. Lett.,

          1996, 68(3): 403.

[6] [6] 3656.

          Cao H, Zhao Y G, Ong H C, et al. Appl. Phys. Lett., 1998, 73(25):

[7] [7] Cho S, Ma J, Sun Y. Applied Physics Letters, 1999, 75(18): 2761.

[8] [8] (10): 7983.

          Vanhensden K, Warren W L, Seager C H, et al. Appl. Phys., 1996, 79

[16] [16] 253.

[17] [17] 2074.