The 4f nonlinear-imaging technique with a phase object (NIT-PO) is a new method to measure the optical nonlinearity of
materials by a single laser shot. A time-resolved pump-probe system based on this technique is constructed by
introducing a pump beam with variable temporal delay, which can simultaneously measure the dynamic nonlinear
absorption and refraction conveniently. Based on this system, we study the dynamic excited-state nonlinearities of the
chloroaluminum phthalocyanine (CAP)/ethanol solution. Dynamic absorption coefficient and refractive index are
deduced through analyzing frames of nonlinear image with different time delays from the standpoint of energy and the
standpoint of information, and some photophysical parameters of the CAP are sequentially validated by theoretically
fitting the experimental curves. On the other side it is demonstrated that the pump-probe system based on 4f NIT-PO
plays a responsible role in simultaneously measuring the dynamic nonlinear absorption and refraction of materials, and
the system could be a good tool for notarizing and characterizing the origins of optical nonlinearities within materials.
We present a new experiment system to improve the original 4f coherent imaging system developed by Georges Boudebs
et al. In the new experiment system we take off the monitor branch, add another 4f system before the main 4f system and
place one more CCD camera after the first 4f system. Our new experiment system has five advantages: firstly, the old
system needs three steps to measure the nonlinear refraction index of the nonlinear sample, however the new system only
needs two steps. Secondly, in the developed system the CCD camera after the first 4f system can monitor the energy
fluctuation as well as the intensity distribution of the input laser pulse, while the original system can only monitor the
energy fluctuation. Thirdly, the new system realizes the real single-pulse measurement, and can avoid the energy
instability completely. Fourthly, in the new system we can detach the diaphragm and the phase object, so they can adjust
separately. Lastly, the added 4f system can be used as a spatial filter. The shortcomings of our improved system are that
the experiment system becomes a little more complex and the additional CCD camera adds the experiment expenditure.
Nonlinear absorptive property of a novel metal cluster cis-Cp*2Mo2S4Cu2I2•(CH2Cl2)2 in CH2Cl2 solution is
studied by using an open-aperture Z-scan technique with laser pulse of 8ns pulse-width at the wavelength of
532nm .The experimental results shows that the cluster has strong nonlinear absorption under the 8ns pulse excitation.
A picosecond time resolved pump-probe experiments at 532nm has been used to study the nonlinear origin of the
cluster. The pump-probe response of the metal cluster is similar to that of C60 solution, which implies that the nonlinear
mechanisms are the same of the two materials. By establishing a five-level model for the cluster, several nonlinear
optical parameters, such as the relaxation time of the excited singlet state, the absorption cross sections of the excited
state of the cluster arc obtained. According to the results of the experiments and numerical simulations, a conclusion can
be obtained that, at 532nm , the effective absorption of the triplet state of the cluster solution is the dominant mechanism
causing the reverse saturable absorption. The theoretical results are in good agreement with the experimental data, which
not only shows the availability of the kinetic model but also demonstrates the close relationship between the nonlinear
absorptive property of the cluster and its dynamic processes.
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