Energy dependent saturable and reverse saturable absorption in cube-like polyaniline/polymethyl methacrylate film

• Synthesized cube-like polyaniline nanostructures.
• Fabricated polyaniline/PMMA nanocomposite films.
• At 5 μJ energy, saturable absorption is observed both at ns and fs regime.
• Switchover from SA to RSA is observed as energy of laser beam increases.
• Film (0.1 wt % polyaniline) shows high βeff (230 cm GW−1) and low limiting threshold at 150 μJ.

Solid films of cube-like polyaniline synthesized by inverse microemulsion polymerization method have been fabricated in a transparent PMMA host by an in situ free radical polymerization technique, and are characterized by spectroscopic and microscopic techniques. The nonlinear optical properties are studied by open aperture Z-scan technique employing 5 ns (532 nm) and 100 fs (800 nm) laser pulses. At the relatively lower laser pulse energy of 5 μJ, the film shows saturable absorption both in the nanosecond and femtosecond excitation domains. An interesting switchover from saturable absorption to reverse saturable absorption is observed at 532 nm when the energy of the nanosecond laser pulses is increased. The nonlinear absorption coefficient increases with increase in polyaniline concentration, with low optical limiting threshold, as required for a good optical limiter.

Figure optionsDownload as PowerPoint slide