Organic nanocrystals grown in gel glasses for optical-power-limiting applications

Nonlinear absorption and optical-limiting properties of sol–gel glasses doped with nanocrystals of stilbene 3 have been studied. These organic–inorganic nanocomposite materials can be highly doped (up to 30 wt %) with active molecules through the control of nanometer-scale crystallization. In the nanosecond time regime, the nonlinear absorption occurs in a two-step process, which is characterized by two-photon absorption and excited-state absorption spectroscopies. In a F/5 optical system, the output energy is damped below 20 μJ for all visible wavelengths, 6 μJ at λ=600 nm. Thus, these nanocomposite materials are a good alternative both to concentrated solutions, due to their stability, and to crystals, due to their isotropic response with polarization.