“…That is why its simplest version, the CQ nonlinearity, attracts significant attention of theoreticians from the early days of nonlinear optics (Zakharov, Sobolev, and Synakh [1971]). Numerical studies have confirmed the stability of fundamental spatial solitons in this system (Wright, Lawrence, Torruellas, and Stegeman [1995]; Dimitrevski, Reimhult, Svensson, Ohgren, Anderson, Berntson, Lisak, and Quiroga-Teixeiro [1998]; Quiroga-Teixeiro, Berntson, and Michinel [1999]). Experimentally a CQ nonlinear dielectric response with positive cubic and negative quintic contributions has been observed in chalcogenide glasses (Smektala, Quemard, Couderc, and Barthelemy [2000]; Boudebs, Cherukulappurath, Leblond, Troles, Smektala, and Sanchez [2003]), and in organic materials (Zhan, Zhang, Zhu, Wang, Li, Li, Lu, Zhao, and Nie [2002]).…”