Photon localization barrier can be overcome

In contradistinction to a widespread belief that the spatial localization of photons is restricted by a power-law falloff of the photon energy density, I.Bialynicki-Birula [Phys. Rev. Lett. 80, 5247 (1998)] has proved that any stronger -- up to an almost exponential -- falloff is allowed. We are showing that for certain specifically designed cylindrical one-photon states the localization is even better in lateral directions. If the photon state is built from the so-called focus wave mode, the falloff in the waist cross-section plane turns out to be quadratically exponential (Gaussian) and such strong localization persists in the course of propagation.Comment: Short communication -- 4 pages, 2 figure

Saari's homographic conjecture for planar equal-mass three-body problem in Newton gravity

Saari's homographic conjecture in N-body problem under the Newton gravity is the following; configurational measure \mu=\sqrt{I}U, which is the product of square root of the moment of inertia I=(\sum m_k)^{-1}\sum m_i m_j r_{ij}^2 and the potential function U=\sum m_i m_j/r_{ij}, is constant if and only if the motion is homographic. Where m_k represents mass of body k and r_{ij} represents distance between bodies i and j. We prove this conjecture for planar equal-mass three-body problem. In this work, we use three sets of shape variables. In the first step, we use \zeta=3q_3/(2(q_2-q_1)) where q_k \in \mathbb{C} represents position of body k. Using r_1=r_{23}/r_{12} and r_2=r_{31}/r_{12} in intermediate step, we finally use \mu itself and \rho=I^{3/2}/(r_{12}r_{23}r_{31}). The shape variables \mu and \rho make our proof simple

Flexural Strength of Interlocking Compressed Earth Brick (ICEB) Unit

This paper presents the flexural strength of the ICEB unit. The flexural strength is important in determining the strength of the masonry unit. About 260 units of ICEB consist three type of unit were tested on flatwise (bed direction) and inverted direction, with the different shape at the top and bottom of the ICEB. The unit was loaded at midspan through a steel bearing plate of 6.4 mm thickness and 38.1 mm width. Specimens were supported at both ends which are free to rotate in the longitudinal and transverse directions during the test. The highest flexural strength of ICEB is Wall Brick for both flatwise and inverted direction which is 2.36 N/mm2 and 2.15 N/mm2, respectively. For flatwise direction, Beam Brick has the lowest flexural strength which is 1.55 N/mm2, and in inverted direction Column Brick flexural strength is lower than Beam Brick which is 1.65 N/mm2. ICEB can be used in construction and has the equal properties as other common brick and block at the market nowadays

Regional differences in the age and growth of red snapper (Lutjanus campechanus) in the US Gulf of Mexico

In the U.S. Gulf of Mexico (GOM), red snapper (Lutjanus campechanus) are managed as a unit stock, although the stock is assessed as subunits east and west of the Mississippi River. Differences were examined between management subunits by comparison of the size and age structure and growth rates of red snapper among recreational catches from 6 regions of the GOM: South Texas, North Texas, Louisiana, Alabama, Northwest Florida, and Central Florida. In all of these regions, red snapper sampled in 2009 and 2010 were small and predominantly from age classes that represented the strong recruitment for the year classes of 2004-06. As such, our data indicate a highly truncated age structure with few fish older than 6 years. Demographic differences in size, age, and growth parameters were found. Small (550 ram in total length), fast-growing individuals dominated the catches in South Texas and the regions of Florida, whereas larger, slower-growing fish represented the majority of catches in Alabama and Louisiana. The potential mechanisms affecting observed demographic variation include environmental differences, fishing pressure, habitat preference, and management regimes; however, no definitive conclusion about cause and effect can be made. The combination of demographic differences between regions and consistent occurrence of the strong year classes GOM-wide supports recent conclusions that red snapper form a metapopulation of semi-isolated assemblages in the GOM

Various Doping Concentration Effect on Silicon-on-Insulator (SOI) Phase Modulator

This paper reports the effect of doping concentration to the electrical characteristic performance of the phase modulator in the carrier injection mode at wavelength 1.55μm. The phase modulator device has been integrated in the silicon-on-insulator (SOI) rib waveguide with the p-i-n diode structure. The electrical device performance is predicted using the 2-D semiconductor package SILVACO (CAD) software under DC operation. The least doping concentration of p+ and n+ region produces the least change of refractive index of the modulator. Meanwhile, results show that by increasing the doping concentrations, the value of I decreases. This means that the phase modulator performance is better with increased doping concentrations

Phase modulator based on Silicon-on-Insulator (SOI) rib waveguide

This paper presents the study of electrical characteristic of phase modulator in the carrier injection mode. The phase modulator device has been integrated in the silicon-oninsulator (SOI) rib waveguide by using the p-i-n diode structure. The electrical device performance is predicted by using the 2-D semiconductor package SILVACO (CAD) software under DC operation. In summary, the phase modulator device required 0.035mA drive current to get phase shift at wavelength 1.55μm meanwhile 0.066mA drive current is required for the 1.3μm wavelength

Electro-Optical Modulator Performance in SOl

Since 1980's, silicon photonic devices have been extensively studied, however a submicrometre-size photonic devices have been realized only in the last few years. Silicon properties namely the transparency in the range of optical telecommunications wavelengths and high index of refraction, have enabled the fabrication of low loss submicron waveguide. Photonic devices such as splitter, coupler, and filter have been demonstrated in silicon but once the device has been fabricated, the properties of the device are predetermined. A silicon based modulator can be used to control the flow of light, where the refractive index of the silicon waveguide can be varied thus, induce a change in the transmission properties. This paper highlights the study of carrier injection effect on silicon waveguide with p-i-n diode structure integrated on Silicon-on-Insulator (SOl). The device performance is predicted using 2D Silvaco CAD software under different applied voltages at 1.55 �m

2x2 Optical Switch Based on Silicon-On-Insulator Microring Resonator

In near future, silicon-on-insulator (SOI) microring resonator are expected to be basic components for wavelength filtering and switching due to their compact size and wide free spectral range (FSR). In this paper, a 2X2 optical switch by using active microring resonator is proposed. The switch is consists of second order serially cascaded microring coupled to a pair of waveguide. The ON/OFF state of the design is control by electric signal which will vary the refractive index. The device is design to operate at 1.55μm wavelength. With a 500nm x 200nm rib dimensions, the design is proven to have single mode behaviour. Finite-Difference Time-Domain (FDTD) method simulation by RSOFT software is use to characterize the device performance. The results show that the 2X2 optical switch proposed can be an efficient device to be functioning in WDM application