A series of alkali metal doped carbon bowls have been designed to optimize the nonlinear optical (NLO) contrast and achieve rapid transformation between ON and OFF states in NLO switch. Transformation among metal doped conformations can be achieved by migration of alkali metal on the bowl surface and bowl-to-bowl inversion. The type of doping agent and doping site on the curved carbon surface significantly influences the amplitude of the first hyperpolarizability of those metal doped systems. Large difference in charge transfer and interaction between the metal and buckybowl is responsible for the large hyperpolarizability contrast among alkali metal doped isomers. (C) 2013 Elsevier B. V. All rights reserved.