Complexity of Polarized Spatial Patterns in Large Area Square VCSEL

We consider pattern selection process in a wide aperture VCSEL near threshold. We show that for a square geometry of the laser aperture, the patterns formed at lasing threshold can be very complicated because of a possible misalignment between directions of an intrinsic spatial anisotropy of VCSEL and lateral boundaries of its aperture. The analogy with quantum billiard structures is established, and fingerprints of wave chaos are found. Influence of localized inhomogeneous in the pump current is also considered.Comment: 10 pages, 8 figures, uses REVTEX

Generation of unipolar half-cycle pulse via unusual reflection of a single-cycle pulse from an optically thin metallic or dielectric layer

We present a significantly different reflection process from an optically thin flat metallic or dielectric layer and propose a strikingly simple method to form approximately unipolar half-cycle optical pulses via reflection of a single-cycle optical pulse. Unipolar pulses in reflection arise due to specifics of effectively one-dimensional pulse propagation. Namely, we show that in considered system the field emitted by a flat medium layer is proportional to the velocity of oscillating medium charges instead of their acceleration as it is usually the case. When the single-cycle pulse interacts with linear optical medium, the oscillation velocity of medium charges can be then forced to keep constant sign throughout the pulse duration. Our results essentially differ from the direct mirror reflection and suggest a possibility of unusual transformations of the few-cycle light pulses in linear optical systems

Использование Питательных Веществ Баранчиками Разного Генотипа

The paper presents the results of a comparative study of feed nutrient utilization in buck lambs with different genotypes under the same growth and management conditions. It has been established that the crossbred and purebred buck lambs have a substantial difference in digestibility of dry and organic matter, as well as protein and fiber. Differences in digestibility of nitrogen-free extractive substances are smaller, although they are significant. Hybrids born to ewes of meat-wool type are superior in terms of feed utilization efficiency in comparison to lambs born to ewes of wool-meat type. The nitrogen balance is also higher in the hybrids. The differences between purebred lambs and hybrids born to ewes of meat-wool type are as follows: hybrids with the Romney Marsh breed – 1.16 g, hybrids with the Kuibyshev breed – 0.1 g. A similar trend is observed for the balance of calcium and phosphorus.El artículo presenta los resultados de un estudio comparativo de la utilización de nutrientes en corderos con diferentes genotipos en las mismas condiciones de crecimiento y manejo. Se ha establecido que los corderos cruzados y de raza pura tienen una diferencia sustancial en la digestibilidad de la materia seca y orgánica, así como de las proteínas y la fibra. Las diferencias en la digestibilidad de las sustancias extractivas sin nitrógeno son más pequeñas, aunque son significativas. Los híbridos nacidos de ovejas del tipo carne-lana son superiores en términos de eficiencia de utilización de alimento en comparación con los corderos nacidos de ovejas del tipo carne-lana. El balance de nitrógeno también es mayor en los híbridos. Las diferencias entre los corderos de raza pura y los híbridos nacidos de ovejas del tipo lana de carne son los siguientes: híbridos con la raza Romney Marsh - 1.16 g, híbridos con la raza Kuibyshev - 0.1 g. Se observa una tendencia similar para el equilibrio de calcio y fósforo.в статье представлены данные по сравнительному изучению использования питательных веществ корма баранчиками разного генотипа в одинаковых условиях вы-ращивания и содержания. Установлено, что у помесных и чистопородных баранчиков наблюдалась значительная разница по переваримости сухого и органического вещества, протеина и клетчатки. По переваримости БЭВ полученные различия менее значительные, хотя и достоверные. При этом следует отметить превосходство помесей, полученных от овцематок мясошерстного типа по эффективности использования кормов по сравнению со сверстниками, полученными от шерстномясных маток. Баланс азота оказался выше также у помесей. При сравнении с чистопородными сверстниками разница у варианта с ромни-марш составила 1,16г, а у варианта с куйбышевской - 0,1г у мясошерстных маток. Аналогичная тенденция и по балансу кальция и фосфора

Features of the crystal structure and electrical properties of sodium chloride at pressure 20-50 GPa

The electrical properties of polycrystalline samples of sodium chloride are studied at direct and alternating current in a wide range of frequencies at high pressure and room temperature. Graphic analysis of the experimental data [1-3] in the view of equivalent circuits allowed us to separate the contributions to conductivity caused by grains and intergrain boundaries. Features of impedance at pressure up to 37 GPa are in good agreement with earlier data and structural changes. It is shown that in the studied materials the electrical resistance of grains is much greater than the resistance of intergrain boundaries. © 2013 Allerton Press, Inc

Coupling of polarization and spatial degrees of freedom of highly divergent emission in broad-area square vertical-cavity surface-emitting lasers

The polarization of highly divergent modes of broad-area square vertical-cavity surface-emitting lasers is shown to be only marginally affected by material anisotropies but determined by an interplay of the polarization properties of the Bragg cavity mirrors and of the transverse boundary conditions. This leads to a locking of the polarization direction to the boundaries and its indeterminacy for wave vectors oriented along the diagonal. We point out a non-Poissonian character of nearest-neighbor frequency spacing distribution and the impossibility of single-wave number solutions

Impedance spectroscopy of synthetic proustite at high pressures

The effect of high pressure (up to 40 GPa) and alternating electric field frequency (100 Hz-500 kHz) on the electrical properties of synthesized single-crystal proustite Ag3AsS3 is studied. The behavior of real and imaginary parts of impedance upon an increase in pressure confirms earlier data on the closing of valence and conduction zones, and on the material's transition to the metal state at ∼30 GPa. © 2013 Allerton Press, Inc

Polarization properties in the transition from below to above lasing threshold in broad-area vertical-cavity surface-emitting lasers

For highly divergent emission of broad-area vertical-cavity surface-emitting lasers (VCSELs) a rotation of the polarization direction by up to 90 degrees occurs when the pump rate approaches the lasing threshold. Well below threshold the polarization is parallel to the direction of the transverse wave vector and is determined by the transmissive properties of the Bragg reflectors that form the cavity mirrors. In contrast, near-threshold and above-threshold emission is more affected by the reflective properties of the reflectors and is predominantly perpendicular to the direction of transverse wave vectors. Two qualitatively different types of polarization transition are demonstrated: an abrupt transition, where the light polarization vanishes at the point of the transition, and a smooth one, where it is significantly nonzero during the transition