• Muller, O.
• Spitzer, D.
• Guerchoux, M.
• Gibot, Pierre
• Merlat, L.

Abstract

International audience ; The optical limiting behavior of templated transition metal nanoparticles Cr 2 O 3 and WO 3 in a PMMA host at the wavelength of 1064 nm in the nanosecond regime is discussed. Optical filters were produced by chemical synthesis from the bulk. The optical limiting properties were characterized using an adequate custom-made optical setup and the third order nonlinear parameters, namely the nonlinear absorption coefficients and refractive indices were measured by the Z-scan method. The optical limiting performance improvement is clearly demonstrated for the PMMA/Cr 2 O 3 filter bearing out a laser protection level of OD = 1.2, a factor of 4 larger than the pure PMMA filter. A significant blue shift in the nonlinear activation threshold energy occurs when WO 3 or Cr 2 O 3 are embedded in a PMMA host as the values have been subsequently pulled down from 500 µJ (pure PMMA) to 65 µJ and 23µJ, respectively. Z-scan measurements highlighted a self-defocusing effect as a result of a negative nonlinearity. Nonlinear refractive indexes in the order of n 2 = −1.0 X 10 −15 cm 2 / W were calculated for the PMMA/Cr 2 O 3 and PMMA/ WO 3 systems. A nonlinear absorption coefficient as high as β = 163 cm / GW was measured for the PMMA/Cr 2 O 3 optical limiting filter while the one for PMMA/ WO 3 lies 1 order of magnitude behind. It is suggested that the PMMA/Cr 2 O 3 optical system undergoes reverse saturable absorption enhanced by excited state absorption (ESA/RSA). Besides, it is believed that multi-photons absorption (MPA) occurs in PMMA/WO 3 or pure PMMA.

Topics

• nanoparticle
• nanocomposite
• impedance spectroscopy
• polymer
• activation