The attenuation or "limitation" of an incoming laser threat to a safe level of radiations using an external element is called optical limitation. The concept of passive laser protection requires the use of materials with nonlinear optical properties that are self-activated when the incident laser threat is above a certain level of intensity. Conjugated polymers are tailored for optical limitation due to their versatility, their non-negligible nonlinear absorption properties and their uniform transmittance characteristics over a broad spectral range, the latter property avoiding color distortions to the observer. Usually, to obtain an optical limiting filter, nanomaterials are dispersed in a polymer host. In this work, we consider polyvinylcarbazole (PVK) as a new polymer host for optical limiting filters. PVK is a high Tg polymer exhibiting a high linear transmittance over a broad spectral range, up to 1.6 μm. The adiabatic bulk polymerization method has been employed to thermally polymerize the monomer in the presence of an initiator. Traces of remaining monomer have qualitatively been monitored using FTIR spectroscopy. Optical limiting experiments have been conducted at the wavelength of 1.06 μm using a Nd:YAG laser source in the nanosecond pulsed regime at a low pulse repetition rate. PVK-based filters present a low nonlinear threshold (i.e. activation of the nonlinear attenuation), a factor of 10 lower than the usual PMMA-based filters. Their global nonlinear attenuation is as high as OD = 2.0.
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