LAUSR

Abstract Dispersive optical nonlinearities in pulsed laser deposited undoped and 5% Al doped NiO thin films reveal negative and positive optical nonlinearities, respectively. The cause of optical nonlinearity is assigned to the presence (absence) of oxygen vacancies in undoped NiO (5% Al doped NiO) thin film which leads to photodensification (photoexpansion) and gives rise to thermo-optic effect. Quite interestingly, the observation of opposite kinds of nonlinearities in a NiO/Al doped NiO bilayer film, leads to the neutralization of the dispersive optical nonlinearity and one expects a resultant optical path length compensation.