Investigation of nitrogen plasma effect on the nonlinear optical properties of PMMA

Effects of low power direct current nitrogen plasma on linear and nonlinear optical properties of red bs dye-doped poly(methyl methacrylate) (pmma) film are studied employing different optical techniques. from spectrometry data, it is shown that applying plasma in such a low range of power does not affect the linear absorption coefficient, linear refractive index, and optical bandgap of this dye-doped polymer; however, nonlinear parameters are changed. experiments are performed using the second harmonic of a continuous nd-yag laser beam at a 532-nm wavelength and 20-mw power. the effect of nonlinear refractive index of red bs dye-doped pmma film in broadening the laser beam is observed. the optical bleaching behavior is investigated by measurement of the intensity of laser beam through the sample. its third-order nonlinearity is measured using close and open z-scan data. nonlinear absorption coefficient and refractive index, as well as real and imaginary parts of the third-order nonlinear optical susceptibility χ3, are changed significantly due to plasma treatment.