Resonant Modes of L-Shaped Gold Nanoparticles

We analyze the electric field modes excited in resonant L-shaped gold nanoparticles using a finite-difference time domain method. Compared to a single gold nanorod, both the odd and even modes of the L-shaped nanoparticles can be excited due to the symmetry breaking. The nanoparticles with equal and unequal arms have different dependence of field enhancement and mode on the incident polarization.     

Crosstalk Noise Reduction in Shift-Multiplexed Holographic Storage System Using Multiple Point Sources

We propose and analyse a new method to reduce cross-talk noise in a shift multiplexed holographic storage system using multiple point sources. The normalized diffraction efficiency is given analytically with respect to the shift distance. The noise-to-signal ratio is defined and calculated to value the cross-talk of the system. The numerical results show that using multiple point sources can effectively decrease the cross-talk.     

Femtosecond Laser Pumped Conical Emission and Seeded Ring Amplification in BBO Crystals

The characteristics of femtosecond laser pumped conical emission in quadratic media of β-barium borate (BBO) crystals are analysed. A minimized dispersion phase-matching angle, by which a wide-range spectrum can be obtained, is used for broadband amplification. When a seed of a chirped supercontinuum pulse is input, it is found that the seed in wavelength 500 nm-750 nm is amplified and time resolved.     

光折变晶体中光互联的研究

对光折变晶体中的光互联进行了研究，提出一种利用桥式互泵浦位相共轭器在同一种光路下实现光开关、广播式、合成式及点点式光互联的方法，同时研究了利用光折变两波耦合进行光互联的强度和时间特性     

All-Optical Modulation with a Surface Plasmon Mach-Zehnder Interferometer

We use two parallel nano-slits in a silver film to form a surface plasmon Mach Zehnder interferometer （MZI）, based on the interference of two surface plasmon waves propagating along the two surfaces of the silver film. Coating the silver film with a photoinduced birefringence polymer film, we achieve optical modulation of the MZI output by changing the refractive index of the polymer film with a pump beam. An on/off ratio 0f 2. 7 is obtained for a probe wavelength of 865 nm.     

SIMULATING STUDY ON INTERNAL SELF-PUMPED PHASE CONJUGATORS WITH EXTERNAL CONFIGURATIONS

A new method is proposed to study the properties of stimulated photorefractive backscat-tering and four-wave-mixing (SPB-FWM) and total-internal-reflection (TIR) self-pumped phase conjugators. The phase conjugators are simulated with external configurations using a KNSBN:Cu crystal, a plane mirror and a prism. As a result, the parameters such as beamwidth and intensity of the contra-directionally propagating pump beams for the FWM interactions in the crystal can be easily controlled. The dependence of self-pumped phase conjugation reflectivity and FWM coupling strength on these parameters of the pump beams have been studied.     

Triple Encrypted Holographic Storage and Digital Holographic System

We propose a triple encrypted holographic memory containing a digital holographic system. The original image is encrypted using double random phase encryption and stored in a LiNbO3：Fe crystal with shift-multiplexing. Both the reference beams of the memory and the digital holographic system are random phase encoded. We theoretically and experimentally demonstrate the encryption and decryption of multiple images and the results show high quality and good fault tolerance. The total key length of this system is larger than 4.7×10^33.     

光折变晶中光互联的研究

对光折变晶体事的光互联进行了研究，提出了一种利用桥式互泵浦位相共轭器在同一种光路下实现光开关，广播式，合成式及点点式光互联的方法，同时研究了利用光折变两波耦合进行了光互联的强度和时间特性。     

Contrast Reversal of Topography Artifacts in a Transmission SNOM

We demonstrate the contrast reversal behaviour of topography artifacts by changing the diameter of the collection diaphragm in a transmission scanning near-field optical microscopy （SNOM）. This originates from the change of the approach curves. Such contrast reversal phenomenon is used to distinguish the artifact signal from the true optical signal of the SNOM image. We also show that continuously changing the diaphragm to a proper diameter can greatly reduce topography artifacts.     

PHOTOCONDUCTIVITY STUDY OF A POTENTIAL PHOTOREFRACTIVE POLYMER

Photoconductive properties of a polymer designed to be photorefractive are investigated. The polymer is composed of photoconducting PVK [poly(n-vinylcarbazole)], photosensitizing TNF (2, 4, 7-trinitro-9-fluorenone), and optically nonlinear DANS (4-N, N-dimethyl-4′-nitrostilbene). The electric-field dependence and λ dependence of its photoconductivity and photocarrier generation efficiency have been measured. And preliminary four-wave mixing experiments have been carried out.