In this paper, a second-order nonlinear interaction, difference-frequency generation, based on three-wave mixing process
in nonlinear multilayered metmaterial has been investigated numerically. The nonlinear multilayered metmaterial is
composed of two periodically alternating metallic and dielectric layers, which their layer thicknesses are reduced into
deep-subwavelength size for creating some nonlinear optical effect enhancement mechanism. The optimal engineered
structure gives a dispersion relation having near zero permittivity at some frequencies and can be called epsilon-nearzero
point. When a pump frequency (ω1) is determined at this point, the epsilon-near-zero phase matched condition and
field intensity enhancement are easily achieved and then a strong idler wave at difference-frequency ω3 = ω1 − ω2,
corresponding to DFG effect can be generated efficiently. According to this parametric interaction, the nonlinear
multilayered metamaterial can be applied as nonlinear frequency converters in various nanophotonic systems.
In this research, the low cost optical tweezers systems using X-Y stage has been developed by using 5-phase stepping motor. By using sequential double coil driving, we can obtain the driving torque larger than using the single coil driving. The moving scale is fine resolution at 0.2 micrometer. The overall systems based on microcontroller PIC18F458 and joystick controller with LabView® graphical user interface (GUI). The mechanical damping has been included in the system for decreasing the vibrational noise. By using this method, our optical tweezers system is cheaper than the other commercial system that has been used the piezoelectric driving, and still has the same efficiency.
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.