Analysis of the influence of thermal effect on Z-scan measurements with a nanosecond pulse laser

The influence of thermally induced optical nonlinearities on Z-scan measure ments with a nanosecond pulse laser is investigated theoretically. The resu lts demonstrate that thermal effect plays an important role in certain circ umstance. As an example, the optical nonlinearities of CS2 with an adjustab le linear absorption coefficient which is used to alter the magnitude of th ermally induced optical nonlinearities are analysed, and the results show t hat thermal effect even makes the change of the sign of optical nonlinearit ies.