[1] G. C. Duree, J. L. Shultz, G. J. Salamo, M. Segev, A. Yariv, B. Crosignani, P. Di Porto, E. J. Sharp, and R. R. Neurgaonkar,Observation of self-trapping an optical beam due to photorefractive effect, Phys. Rev. Lett., 71 (1993) 533.
[2] W. L. She, K. K. Lee, W. K. Lee,All Optical Quasi-Steady-State Photorefractive Spatial Solitons,Phys. Rev. Lett. 85 (2000) 2498.
[3] J. Liu, Z. Hao, Evolution of separate screening soliton pairs in a biased series photorefractive crystal circuit, Phys. Rev. E, 65 (2002) 066601.
[4] M. Segev, G. C. Valley, B. Crosignani, P. Diporto, A. Yariv, Steady-State Spatial Screening Soliton in Photorefractive Materials with External Applied Field, Phys. Rev. Lett, 73 (1994) 3211.
[5] K. Kos, H. Meng, G. Salamo, M. F. Shih, M. Segev, G. C. Valley,One-dimensional steady-state photorefractive screening solitons, Phys. Rev., E, 53 (1996) 4330.
[6] Z. Chen, M. Mitchell, M. Shih, M. Segev, M. H. Garrett, G. C. Valley, Steady-state dark photorefractive screening solitons, Opt. Lett., 21 (1996) 629.
[7] D. N. Christodoulides, S. R. Singh, M. I. Carvalho, M. Segev, Incoherently coupled soliton pairs in biased photorefractive crystals, Appl. Phys. Lett., 68 (1996) 1763.
[8] L. Jin-song, Universal theory of steady-state one-dimensional photorefractive solitons, Chin. Phys, 10 (2001) 1037.
[9] N. Asif, S. Shwetanshumala, S. Konar,Photovoltaic spatial solitons pairs in two-photon photorefractive materials, Phys. Lett. A, 372 (2008) 735.
[10] M. Segev, G. C. Valley, M. C. Bashaw, M. Taya , M. M. Fejer,Photovoltaic spatial solitons, J. Opt. Soc. Am. B, 14 (1997) 1772.
[11] J. Liu, L. Keqing, Screening-photovoltaic solitons in a biased photovoltaic-photorefractive crystals and their self-deflection, J. Opt. Soc. Am. B, 16 (1999) 550.
[12] G. Zhang, J. Liu, Screening-photovoltaic spatial solitons in a biased two-photon photovoltaic-photorefractive crystals, J. Opt. Soc. Am. B, 26(2008) 113.
[13] J. Liu,Separate spatial soliton pairs and solitons interaction in an unbiased series photorefractive crystal circuit, Phys. Lett. A, 300 (2002) 213.
[14] X. Ji, Q. Jiang, J. Yao, J. Liu,Separate spatial soliton pairs in an unbiased series two-photon photorefractive crystal circuit,Opt. Laser. Technol, 42 (2009) 322.
[15] E. Castro-Camus, L. F. Magana,Prediction of the physical response for the two-photon photorefractive effect, Opt. Lett. 28 (2003) 1129.
[16] Y. Zhang, C. Hou, K. Zhan, X. Sun, Incoherently coupled bright–dark photovoltaic soliton pairs based on two-photon photorefractive effect, Optik-Int. J. Light Electron Opt, 122(2011) 263.
[17] Y. Zhang, C. Hou, F. Wang, X. Sun, Optik, Incoherently coupled grey–grey spatial soliton pairs due to two-photon photorefractive media, 119(2008) 700.
[18] K. Lu, W. Zhao, Y. Yang,Y. Yang, R.A. Rupp, M. Fally, Y. Zhang, J. Xu, M. Zhang,One-dimensional incoherently coupled grey solitons in two-photon photorefractive media , Appl. Phys. B, 87 (2007) 469.
[19] K. Kuroda,Progress in photorefractive Nonlinear Optics, Taylor and Francis, 2002.
[20] G. Stegemen,Optical spatial solitons: Historical perspectives,IEEE J. Select Top Quantum Electron, 6 (2000) 1419.
[21] G. Evans, J. Blackledge, P. Yardley, Numerical methods for partial differential equation, Springer Verlag, Berlin, 2000.
[22] A. Keshavarz, L. Sadralsadati, M. Hatami,Simulation of soliton propagation in photovoltaic photorefractive two-photon materials and study the switching behavior, PIERS Proceeding, Moscow, Russia, August18-21, 2009, 1823.