Hye Ri Yang

Orientational photorefractive holograms in porphyrin:Zn-doped nematic liquid crystals

We investigated the diffraction properties of dynamic holograms recorded in porphyrin:Zn doped nematic liquid crystals (NLCs) under the influence of an applied dc electric field for various conditions of the grating period, the writing beam intensity and the applied electric field. We also derived an analytic expression for diffraction efficiency from NLCs material equations and torque balance equations and compared the experimental results with the theory, revealing excellent agreement.

Kinetics of two wave mixing gain for moving grating technique in photorefractive BaTiO 3 crystal

We present analytic expressions for time-dependent space charge field and two wave mixing gain under the external applied field accompanying the grating translation. The variations of complex space charge field are analyzed in a complex plane, and the explicit expressions for the resonance and optimum frequencies (or moving grating velocities), which maximize the magnitude and imaginary part of space charge field, respectively, are also obtained. In addition, two wave mixing experiment was conducted with a grating translation technique without the external applied field in a BaTiO(3) crystal and the transient behaviors of measured gain look like damped harmonic oscillations, showing excellent agreement with the theory for the entire time range.

Sequential Variations of Fraunhofer Diffraction Pattern by Optical 4f Imaging System in As 2 S 3 Thin Film

We observed sequential changes of Fraunhofer diffraction pattern due to photoinduced nonlinear refractive index changes in chalcogenide amorphous AS2S3 thin film by utilizing the optical 4f imaging system and also measured the power distribution of the temporal observed patterns.

Study on Holographic Diffraction Properties in Dye-doped Nematic Liquid Crystals

We measured the diffraction efficiency in porphyrin:Zn doped nematic liquid crystals by using a two beam coupling experiment under the influence of an applied dc field. The maximum diffraction efficiency of eta = 38.7% was obtained with a writing beam intensity of 207 mW/cm2 and an electric field of 1.28 V / mum.

Z-scan measurement for two photon absorption and Kerr coefficients in amorphous chalcogenide As/sub 3/S/sub 3/ thin film

We performed openand closed-aperture Z-scan experiments in amorphous chalcogenide As2S3 thin film and also present Z-scan theory. Both nonlinear Kerr coefficient and two photon absorption coefficient of As2S3 were determined.

Two beam coupling gain enhancement in porphyrin:Zn-doped nematic liquid crystals with an applied DC field and moving grating technique

We measured two beam coupling gain in porphyrin:Zn-doped nematic liquid crystals with an applied dc field by using the moving grating technique and theoretically derived an expression of the gain coefficient, showing good agreement with the experimental results.

Z-scan analysis of porphyrin:Zn doped nematic liquid crystal

We measured Z-scan transmittance in porphyrin:Zn doped nematic liquid crystal and developed Z-scan theories for plausible physical mechanisms such as Kerr, thermo-optic and saturable Kerr effects. It is shown that the saturable Kerr effect is most relevant physical origin of our sample.

Variational Analysis of Z-scan in a Saturable Kerr-like LiNbO 3 Crystal

By using the variational formulation, we analyzed the beam waist profile and the Z-scan transmittance in a thick saturable Kerr medium. We also measured Z-scan transmittance in a saturable Kerr-like LiNbO3and compared with the variational analysis.

Simultaneous measurements of two wave mixing gain and diffraction efficiency in photorefractive BaTiO/sub 3/ crystal

We present a novel method for simultaneously measuring two wave mixing gain and diffraction efficiency and measured transient gain coefficients against tilt angle between the grating wave vector and c-axis in a photorefractive BaTiO/sub 3 /crystal.

Measurement and analysis of photoinduced birefringence in a methylorange-doped PVA film

We fabricated methylorange (MO) doped PVA thin film for various concentrations of methylorange and measured the photoinduced birefringence of MO/PVA thin film by means of the pump-probe technique. The experimental results were analyzed by adopting empirical stretched-exponential kinetics.