Fabrication and evaluation of photonic metamaterial crystal

Many researching efforts have been reported to seek various fundamental LC resonance structures, recently. But still the Split Ring Resonator (SRR) is the most famous and major fundamental LC-resonance structure used in the metamaterial. We employed SRR structure as the fundamental LC-resonance mechanism to fabricate photonic crystal with periodic arrangement of two different metamaterial areas composed from SRR arrays on the dielectric substrate. We developed Photonic Metamaterial Crystal (PMC) to realize the more advanced and versatile functions of the metamaterial by 1 dimensional or 2 dimensional periodic arranging of two metamaterial sections which have different dispersion properties due to the different size of SRR structures each other. In this paper, we report the fabrication process, estimation of PMC properties and some possible future application prospects, for instance the PMC waveguide structures and nonlinear properties of PMC observed as selective LC-resonant properties in Raman mapping analysis of PMC. These are quite interesting characters of PMC and the attractive applications as the PMC devices.     

Sonochemically synthesized core-shell structured Au–Pd nanoparticles supported on γ-Fe2O3 particles

A sample of Au–Pd bimetallic nanoparticles supported on γ-Fe₂O₃ was synthesized in a sonochemically one-pot process. The structural analyses of the synthesized sample were performed by the techniques of X-ray Absorption Fine Structure (XAFS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and UV–vis spectrometry. Results indicated that the synthesized sample formed a core-shell structure in which a gold core was surrounded by a thin palladium shell. The reaction rate constant for the hydrogenation of cyclohexene of the present sample showed higher value than that of Pd nanoparticles supported on γ-Fe₂O₃ and core-shell structured Au–Pd nanoparticles supported on SiO₂. The present sample is a promising catalyst material which has a high catalytic activity.     

Proposal of a frequency-synthesis chain between the microwave and optical frequencies of the Ca intercombination line at 657 nm using diode lasers

We propose a frequency synthesis chain which can directly connect a microwave atomic clock with a visible laser. We design this chain for the frequency measurement of a visible laser locked on the intercombination transition of Ca at 657 nm. The proposed chain is based on both an optical difference frequency divider and an optical frequency comb generator, and it is designed to use nine visible and near-infrared diode lasers. We discuss the technical requirements to realize the frequency measurement accuracy level of 10^–14.     

Playback performance of perpendicular magnetic recording tape media for over-50-TB cartridge by facing targets sputtering method

Perpendicular magnetic recording tape medium with laminated soft magnetic underlayers was successively formed on a 4.5 μm thin plastic film by the facing targets sputtering method at room temperature. The tape medium showed extremely high SNR values with sharp transitions in playback tests by a drum tester, compared to a linear format commercial tape medium. An areal density of 45.0 Gb/in.² of perpendicular tape medium was confirmed by a high-resolution contact tester. These results suggest that the perpendicular recording tape medium by the facing targets sputtering method is a promising candidate for a tape cartridge of over 50-TB.     

Evaluation of zinc self-diffusion at the interface between homoepitaxial ZnO thin films and (0001) ZnO substrates

Isotopic ZnO thin films were deposited on the c-plane of ZnO single crystals by pulsed laser deposition. The isotopic abundance of Zn in the films was determined with a secondary ion mass spectrometry before and after the films was diffusion annealed. The diffusion profiles across the film/substrate interface behaved smooth features. The zinc diffusion coefficient (D_Zn) was obtained by analyzing the slope of the profile in the annealed sample. The temperature dependence of D_Zn was determined to be D_Zn(cm²/s)=8.0×10⁴exp(?417[kJ/mol])/RT, where R and T are gas constant and temperature. The zinc ion diffusion coefficients were of the same order as that in a ZnO single crystal. A comparison of the experimental and theoretical values indicated that the zinc ions diffused in the thin film and the single crystal through a vacancy mechanism.     

Direct conversion of a metal organic compound to epitaxial Sb-doped SnO2 film on a (0 0 1) TiO2 substrate using a KrF laser, and its resulting electrical properties

Epitaxial Sb-doped SnO₂ (0 0 1) thin film on a TiO₂ (0 0 1) substrate was successfully prepared by laser-assisted metal organic deposition at room temperature. The effects of the precursor thin film and laser fluence on the resistivity, carrier concentration, and mobility of the Sb-doped SnO₂ film were investigated. The resistivity of the Sb-doped SnO₂ film prepared by direct irradiation to metal organic film is one order of magnitude lower than that of film prepared by irradiation to amorphous Sb-doped SnO₂ film. From an analysis of Hall measurements, the difference between the resistivity of the Sb-doped SnO₂ film prepared using the metal organic precursor film and that of amorphous precursor film appears to be caused by the mobility. Direct conversion of the metal organic compound by excimer laser irradiation was found to be effective for preparing epitaxial Sb-doped SnO₂ film with low resistivity.     

Preparation of Y2O3:Eu thin films by excimer-laser-assisted metal organic deposition

Europium-doped yttrium oxide (Y₂O₃:Eu) thin films were successfully deposited on quartz and ITO/glass substrates by excimer-laser-assisted metal organic deposition (ELAMOD) at low temperatures. The effects of laser wavelength and thermal temperature on the films’ crystallinity and photoluminescence properties were investigated. Films irradiated by an ArF laser at 80 mJ/cm² and 400–500°C were highly crystallized compared with those prepared by thermal MOD. In contrast, when the film was irradiated by a KrF laser at 500°C, no crystalline Y₂O₃:Eu was formed. The Y₂O₃:Eu film irradiated by the ArF laser at 80 mJ/cm² and 500°C showed typical PL spectra of Eu³⁺ ions with cubic symmetry and a ⁵D₀→⁷F₂ transition at ∼612 nm. The PL intensity at 612 nm was much higher for the film prepared with ELAMOD than for that prepared by the thermal-assisted process, and the photoemission intensity of the film prepared with ELAMOD strongly depended on the substrate material.     

Antikaon–Nucleon Dynamics and its Application to Few-Body Systems

We overview the recent progress in the investigation of the antikaon dynamics with single nucleon and with few-body nuclei, based on chiral SU(3) symmetry. We first show how the Λ(1405) resonance emerges from the coupled-channel ${\bar{K}N - \pi\Sigma}$ interaction. Next, we present the construction of an up-to-date ${\bar{K}N}$ interaction in response to the recent measurement of kaonic hydrogen. Finally, we discuss the possibility of the antikaon bound states in nuclei from the perspective of few-body physics.     

Two unstable oscillations in the multimode laser with modulated inversion

We present comprehensive results of numerical studies on the dynamical properties of a multimode ring laser under modulation of the population inversion in the bad-cavity condition. Incoherent properties of unstable oscillations in this system are investigated in detail as a function of two control parameters: the dc component of the population inversion and the modulation amplitude. Two kinds of optical chaos in two limiting regions reported in a previous paper are extensively studied to clarify their different characteristics from deterministic and stochastic points of view. The competition between their different origins is revealed. Statistical properties of their stochasticity are investigated to clarify their non-Gaussian natures. Comparison with analytical results for a single-mode laser with fluctuations is also made.     

Optical Phase Conjugation in Polyesters with Cyanoazobenzene Units in the Side Chain

Efficient optical phase-conjugate (PC) signals in four kinds of novel polyester films containing cyanoazobenzene units in the side chain are reported. One of them can efficiently generate only the photoinduced anisotropy (PA) component of PC signal, while the other three films can simultaneously generate two types of PC signals, PA and holographic components. These polymers have good potential not only as a phase conjugator but also as a polarization-sensitive hologram-recording material.Presented at the International Commission for Optics Topical Meeting, Kyoto, 1994