Formation characteristics of dark solitons in photorefractive crystals having both linear and quadratic electro-optic effect simultaneously

The temporal behavior and formation characteristics have been investigated for the first time in nonlinear optical media exhibiting photorefractive effect due to simultaneous linear and quadratic electro-optic effect. The space charge field which is a function of time is derived and hence leads to the time dependent wave equation satisfied by light beams in such novel photorefractive materials. The soliton width evolution and hence the evolution of the nonlinearity with time is investigated for different values of peak intensity ratio. The dark soliton formation does not show quasi steady state behaviour and only steady state solitons are formed. There is interplay between the linear and quadratic electro-optic effect that affects the formation of dark solitons. Finally, the effect of crystal temperature on the formation of dark solitons is studied. In a photorefractive crystal, the temperature modification results in consequent changes in dark irradiance and dielectric constant which has a profound effect on the time evolution of these dark solitons. A relevant example of 0.67PMN-0.33PT crystal has been considered for an illustration of our results.