A Comparative Study of Third-Order Electronic and Thermally Induced Optical Nonlinearity in Rodamin 610 Doped PMMA Thin Film

F. Jaffar, Amal

	A Comparative Study of Third-Order Electronic and Thermally Induced Optical Nonlinearity in Rodamin 610 Doped PMMA Thin Film
Al-Mustansiriyah Journal of Science
Article 1, Volume 24, Issue 2, 2013, Pages 89-102
Author
Amal F. Jaffar
Abstract
Third-order optical nonlinearities of Rodamin610 (R610) doped polymer thin films with thicknesses in the range of (171_191) µm, with different concentrations were investigated using Nd: YAG pulsed laser with nanosecond pulses at 532 nm and continuous-wave (CW) of diode laser at 650 nm. The optical nonlinearity (nonlinear refraction index, nonlinear absorption coefficient and third order nonlinear susceptibility) measured by using z-scan technique: closed and open aperture methods. It was found that the optical nonlinear properties with closed aperture has negative nonlinearity (defocusing),with open aperture has positive nonlinearity (two photon absorption) and it is increased with the increasing of films concentration due to the increasing of the film thickness which caused increasing the nonlinear phase shift in the samples. The results indicate that the values of the nonlinear refractive index measured with CW diode laser are larger that measured with ND: YAG pulsed laser. The nonlinearity with the pulsed laser input was mainly electronic in origin, and with a CW diode laser was thermal in origin. Local heating in the polymer film by light absorption is thought to be a cause of the large nonlinearity by using CW laser. The results imply that R610 films can be used as a potential medium for various optoelectronic applications including that in optical power limiting.

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