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Higher-order anisotropic self-diffraction up to third orders have been observed in Cerium doped barium titanate by using red beam at 633 nm from He-Ne laser. In our experiment, the third orders and second orders have been observed simultaneously for the first time from our knowledge. From our observation, the phase conjugate beam has not been generated before and after the appearance of higher orders as observing when the green beam from the Argon-ion laser at 514.5 nm has been used. The diffraction efficiency and the decay rate of the grating have been measured as well in the red light case

We describe two optical tweezer systems for the studies of laser trapping of fluorescent colloidal nanoparticles (NPs). The first one, conventional optical tweezer system widely used in laser trapping, requires a fluorescent confocal microscope for observing trapped NPs. The second system, with no microscope, is presented for the first time in this work. The quantity of trapped NPs for this system is estimated from the transmitted laser light intensity that passes through the fluorescent colloidal NPs. Then the transmitted laser light is converted into the voltage signal and measured by an oscilloscope. A small capillary tube to be filled by the colloidal NPs is developed and used in the second system. This tube can be used with light-sensitive cameras for which a danger of damaging by high light intensities exists. Finally, we show that the results obtained using the both tweezer systems are in good agreement.