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The Effects of Pulsed Laser Irradiation on the Nonlinear Optical Properties of Poly(methyl methacrylate) (PMMA) Film
S. Zahedi and D. Dorranian

A Nd:YAG pulsed laser was used for treatment of red BS dye doped Poly(methyl methacrylate) (PMMA) films. Films were irradiated with 30, 50, and 100 numbers of 6 ns laser pulse at 532 nm wavelength and 600 mJ pulse energy. In this manuscript the effect of laser pulse number on the linear and nonlinear optical properties of films is investigated in detail. Nonlinear optical properties of samples were studied experimentally employing different optical techniques. Experiments were performed using the continuous Nd-YAG laser beam at 532 nm wavelength and 20 mW power. Broadening the beam profile after propagating through the samples has been observed. The nonlinear absorption coefficient of samples has been calculated using open aperture Z-scan data while their nonlinear refractive index has been measured using the closed aperture Z-scan data. Real and imaginary parts of the third-order nonlinear optical susceptibility, X(3), were changed significantly with the number of laser pulse in treatment.

Keywords: Disc laser, laser welding, stainless steel, ultrasonic testing, weld width, C-scan

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