Gap solitons in one-dimensional χ(2) hetero-structures induced by the thermo-optic effect

The existence of stable optical spatial solitons in a one-dimensional periodic stack whose unit cell is composed of two quadratic nonlinear materials is demonstrated. The stack is subjected to an array of micro-heaters, arranged in such a way that a periodic temperature gradient imposed upon the original structure, induces a variation of the refractive index due to the thermo-optic effect. Within a multiple scale approach the governing wave equations are obtained. A linear stability analysis together with the numerical evolution of these equations are carried out, evidencing distinctive soliton dynamics. By varying parameters like the period and the depth of the temperature modulation one is able to steer these solitons, to change their shape and, move them independently.