A modified pump-probe method for sensitive measurement of optical nonlinearity

We have proposed an effective and convenient technique called coaxial pump-probe technique, which is implemented with two obscuration disks, to investigate the dynamics of nonlinear absorption in materials. Compared to the traditional pump-probe technique, the measurement sensitivity and capability of the system is enhanced by increasing the effective overlap region of pump and probe beams. Moreover, this technique facilitates the utilization of arbitrary polarizations and wavelengths for the pump and probe beams. The efficacy of the proposed method is demonstrated by measuring the nonlinear optical properties of zinc selenide, cadmium selenide and a symmetrical phenoxazinium bromine salt solution at different wavelengths.