[1] Segev M, Crosignani B, Yariv A, et al. Spatial solitons in photorefractive media [J]. Phys. Rev. Lett., 1992, 68(7): 923-926.
[2] Duree G C, shultz J L, Salamo G J, et al. Observation of self-trapping of an optical beam due to the photorefractive effect [J]. Phys. Rev. Lett., 1993, 71(4): 533-536.
[3] Christodoulides D N, Carvalho M I. Bright, dark, and gray spatial soliton states in photorefractive media [J]. J. Opt. Soc. Am. B, 1995, 12(9): 1628-1633.
[4] Segev M, Valley G C, Bashaw M C, et al. Photovoltaic spatial solitons [J]. J. Opt. Soc. Am. B, 1997, 14(7): 1772-1781.
[7] Christodoulides D N, Singh S R, et al. Incoherently coupled soliton pairs in biased photorefractive crystals [J]. Appl. Phys. Lett., 1996, 68(13): 1763-1765.
[8] Chen Z, Segev M, Coskun T H, et al. Coupled photorefractive spatial-soliton pairs [J]. J. Opt. Soc. Am. B, 1997, 14(11): 3066-3077.
[11] Castro-Camus E, Magana L F. Prediction of the physical response for the two-photon photorefractive effect [J]. Opt. Lett., 2003, 28(13): 1129-1131.
[12] Hou Chunfeng, Pei Yanbo, Zhou Zhongxiang, et al. Spatial solitons in two-photon photorefractive media [J]. Phys. Rev. A, 2005, 71(5): 053817.
[13] Hou Chunfeng, Zhang Yu, Jiang Yongyuan, et al. Photovoltaic solitons in two-photon photorefractive materials under open-circuit conditions [J]. Opt. Commun., 2007, 273(2): 544-548.
[14] Zhang Yu, Hou Chunfeng, Sun Xiudong. Grey spatial solitons due to two-photon photorefractive effect [J]. Chin. Phys., 2007, 1(1): 159-164.
[16] Zhang Guangyong, Liu Jinsong. Screening-photovoltaic spatial solitons in biased two-photon photovoltaic photorefractive crystals [J]. J. Opt. Soc. Am. B, 2009, 2(1): 113-120.