In this paper, we investigate the nonlinear optical properties of unsymmetrical trimethine cyanine dyes(ethyl-4-(3-(3-ethylbenzo[d]xazole-2(3H)-ylidene)prop-1-en-1-yl)quinolin-1-iumiodidebenzo[d]xa zole group) by conducting Z-scan technique at 532 nm and time-resolved pump probe with phase object (POPP). Pronounced reverse saturable absorption (RSA) and positive refraction are observed. Moreover, the relevant third-order NLO photo-physical parameters of unsymmetrical trimethine cyanine dyes determined unambiguously.
The third-order nonlinear optical response of molybdenum disulfide dissolved in ethanol was investigated using a modified time-resolved pumpeprobe measurement with phase object at 532 nm with pico-second laser pulse. The experimental results clearly indicate that the observed nonlinear response should be of excited-state origin. The compound exhibits strong saturable absorption and long excited-state lifetimes. The nonlinear absorptive and refractive parameters of the phenoxazinium salt were evaluated by combination of picosecond pumpeprobe measurements and picosecond Z-Scan experiments. The experiment results demonstrate this compound is a promising nonlinear optical material.
The optical nonlinearities of semiconductor bulk material Indium nitride (InN) have been investigated by Reflection Z-scan technique (RZ-scan) at the wavelength of 532nm with 21ps laser pulse. Top hat beam is used in order to get high spatial quality. Different from the normal RZ-scan device, instead of moving the sample, the lens before the sample is moved along z-axis. This can guarantee the stability of the spot on the surface of the sample and the measurement accuracy. The measurement of nonlinear refraction without aperture should be tested first, and then with a small aperture nonlinear absorption coefficient is measured. The experimental results show that InN has positive nonlinear refraction and saturable absorption effect. Nonlinear refraction and absorption coefficient are obtained by fitting theoretical simulation with experimental data.
In this paper, we present a new technology to enhance the sensitivity by absorbing part of the light at the entry of the Z-scan system. Compared to the top-hat Z-scan, the curves of the modified top-hat Z-scan for the nonlinear refraction show higher peak-to-valley values, which mean higher sensitivity with our modified method. Nonlinear refraction of CS2 is investigated using this technique with 19ps pulses at wavelength of 532 nm.
Lanthanide doped oxides nano materials have novel optical, physical and structural properties. Cubic
Ho3+-Yb3+-Tm3+ co-doped Gd2O3 nanotubes are synthetize by a simple wet-chemical route at low temperature and
ambient pressure followed by subsequent annealing heat treatment in muffle furnace. Nanotubes are formed by adjusting
the pH value of reacting solution. The introduction of Yb3+ leads to strong visible upconversion luminescence and
change the intensity ratio of the green, blue and red luminescence. In trichromatic laser display, research of how to
enhance blue light is in the bottleneck period. In the experiment, the blue emission has been successfully improved. In
certain doping ratio, distinct enhancement of blue emission and obvious degradation of green light have been observed,
which is discussed in detail. X-Ray powder diffraction (XRD), scanning electron microscope (SEM) and upconversion
(UC) emission spectra are used to characterize the sample. Strong and adjusted upconversion luminescence determine
that the nano material is a potential candidate for applications of biological probe, color displays, lighting and photonics.
The optical nonlinearities of bulk GaN single crystal are investigated by conducting Z-scan experimental measurements, using nanosecond pulses at 532nm. The material’s nonlinear absorptive and refractive optical nonlinearities are determined by measuring the normalized transmittance with and without an aperture in the far field. After simulating the experimental curves, the two-photon absorption (TPA) coefficient, especially the refractive-index change induced by two-photon-excited free carrier, are obtained. The experimental results show that GaN has reverse saturable absorption and self-defocusing effect at 532 nm, indicating this material is a good candidate for future photonics applications. The theoretical simulation fit well with experimental results.
A new organic material 4-hydroxy-ethyl-phenyl-porphyrin-3-propionate was investigated due to its favorable nonlinear absorptive and refractive properties using a modified time-resolved pump-probe system with phase object at 532 nm under picosecond pulse excitation. A five-level model was used to explain the optical nonlinearity of the sample. With the corresponding fitting program, the nonlinear coefficients of the sample were obtained.
The nonlinear refractive response of a copper phthalocyanine film fabricated by the electro-deposition is
investigated by a modified top-hat Z-scan with 19 picoseconds pulse at wavelength of 532 nm. Compared to the top-hat
Z-scan, the curve of modified top-hat Z-scan for the nonlinear refraction shows a single peak rather than a peek-valley
curve. Furthermore, the sensitivity of this new technique can be more than two orders of magnitude enhanced. The
results show that the film has obvious response of nonlinear refraction. The theoretical simulation fit well with