Three-color photonic crystal demultiplexer based on ultralow-refractive-index metamaterial technology

We numerically demonstrate the operation of a novel class of wavelength-division demultiplexing circuit based on photonic crystal waveguides that are entirely synthesized by ultralow-refractive-index metallic nanopillars. The operational principle of the newly proposed device is based on the phenomenon of total external reflections in ultralow-refractive-index metallic photonic crystal structures (metamaterials). In addition we provide detailed design guidelines for optimum device performance. The low propagation losses and compact size, as well as temperature-insensitive operation over a wide temperature range, are only a few of the advantages of the proposed technology, making this new type of demultiplexer an excellent candidate for applications in the visible spectrum.     

KAMIOKA nucleon decay experiment

Summary Recent results of KAMIOKA nucleon decay experiment are presented. The great majority, ∼95%, of the contained events can be naturally explained as due to the atmospheric neutrinos,i.e. the rate and the momentum distribution of the pseudoelastic ν_μ and ν_e events and the multiplicity distribution. However, 5 multiple-ring events remain each defying this interpretation at 90% c.l. Stringent flux upper limits are obtained for magnetic monopole from the searches for Rubakov effect in the detector and in the Sun. KAMIOKANDE collaboration:K. Arisaka, T. Kajita, T. Kifune, M. Koshiba, K. Miyano, M. Nakahata, Y. Oyama, T. Suda, A. Suzuki, K. Takahashi, M. Takita andY. Totsuka: ICEPP and Department of Physics, University of Tokyo; Institute of Cosmic Ray Research, University of Tokyo; KEK, National Laboratory for High Energy Physics and Department of Physics, Niigata University. (As of January 1985,K. Arisaka moved to Department of Physics, Pennsilvania University.)     

Theoretical realization of holey fiber with flat chromatic dispersion and large mode area: an intriguing defected approach

We present a novel design approach for realizing holey fibers (HFs) with flat dispersion characteristics and large mode area based on the existence of an artificially defected air-hole ring in the cladding, and on the inclusion of additional defected air holes in the core of the fiber. This unique type of HF can be used for achieving remarkable flat dispersion characteristics as well as a large mode area, which are particularly useful for high-speed data transmission. The validation of the proposed design is done by adopting an efficient full-vectorial finite element method for optical characterization of HFs. The proposed fiber can be employed in reconfigurable optical transmission systems for performing wavelength division multiplexing operation. Typical characteristics of the proposed HF are a flattened dispersion of 6.3 +/- 0.5 ps/km/nm from 1.45 to 1.65 microm and an effective mode area as large as 100 microm2 in the same frequency range.     

Design of ultra compact all-optical XOR and AND logic gates with low power consumption

We propose a novel ultra-compact all-optical XOR and AND logic gates without using nonlinear optics. In order to realize these devices, we adopt photonic crystal waveguides (PCWs) based on multi-mode interference devices. Numerical results show that the operating bandwidth of the ON to OFF logic-level contrast ratio of not less than 6.79 dB is 35 nm for XOR logic gate and 9 nm for AND logic gate. Proposed logic gates have the potential to be key components for an optical packet switching system due to their small feature sizes and low power consumption.     

Fermi-Dirac Kink Propagation in High-Order Nonlinear Media

We show analytically that addition of a quintic term to the positive Kerr-type nonlinearity offers a unique type of kink soliton-like solution with Fermi-Dirac profile. This type of optical kink allows, in contrast to other optical kinks discovered so far, stationary kink formation not only in the time domain but in the spatial domain. The latter could admit of a route for the first time to our knowledge to spatial kink solitons of intensified laser beams. The underlying principle of the optical kink propagation is described.