Investigation on the Formation of Laser Transverse Pattern Possessing Optical Lattices

Optical lattices (OLs) with diverse transverse patterns and optical vortex lattices (OVLs) with special phase singularities have played important roles in the fields of atomic cooling, particle manipulation, quantum entanglement, and optical communication. As a matter of consensus until now, the OL patterns are generated by coherently superimposing multiple transverse modes with a fixed phase difference through the transverse mode locking (TML) effect. There are phase singularities in the dark area of this kind of OL pattern, so it is also called OVL pattern. However, in our research, it is found that some high-order complex symmetric OL patterns can hardly be analyzed by TML model. Instead, the analysis method of incoherent superposition of mode intensity could be applied. The OL pattern obtained by this method can be regarded as in non-TML state. Therefore, in this article, we mainly study the distinct characteristics and properties of OL patterns in TML and non-TML states. Through intensity comparison, interferometry, and beat frequency spectrum, we can effectively distinguish OL pattern in TML and non-TML states, which is of significance to explore the formation of laser transverse pattern possessing OL.

POTENTIAL RISK OF LOSSES IN MAIZE CAUSED BY Dichelops melacanthus (DALLAS) (HEMIPTERA: PENTATOMIDAE) IN BRAZIL

ABSTRACT: The incidence of the green belly stink bug, Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae),on maize crop in Brazil has increased with time, especially due to the continuous availability of food throughout theyear. This insect causes injury to seedlings, killing them shortly after their emergence from the soil. If the plant survives,it is possible to see areas with necrotic lesion that increase in a transverse pattern on the sheet, with perforations on theleaves or tillers (side shoots). This pest is currently one of the most important to maize, in conventional and Bt hybrids.The research compared the behavior of theses cultivars infested by the green belly stink bug, D. melacanthus. Bt andconventional maize cultivars were evaluated in a protected environment (greenhouse) and only Bt maize was evaluatedat field. Evaluations based on plant development and insect injury occurred after seven days of the infestation period.The results indicated variability among cultivars related to insect infestation, measured by a visual scale for damagedetermination and plant development. Grain yield obtained from infested plots was 6352.2 kg ha-1 whereas in the noninfestedplots was 8048.05 kg ha-1, equivalent to an average reduction of 21.07%.Keywords: Plant damage, grain losses, green belly stink bug.RISCO POTENCIAL DE PERDAS CAUSADAS POR Dichelops melacanthus (DALLAS)(HEMIPTERA: PENTATOMIDAE) EM MILHO NO BRASILRESUMO - A incidência do percevejo barriga verde Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae)em milho no Brasil tem aumentado nos últimos anos, especialmente devido à disponibilidade de alimento o ano todo.A injuria provocada pelo inseto pode causar a morte da plântula reduzindo o número ideal de plantas na colheita.Se a planta sobrevive, é possível visualizar áreas necrosadas ou perfilhamento. A praga é atualmente uma das maisimportantes do milho, tanto em cultivares convencionais como em cultivares Bt. A presente pesquisa comparou ocomportamento destas cultivares em ambiente protegido (casa de vegetação) e no campo, avaliando a injuria provocadapela praga, o desenvolvimento da planta e a produtividade de grãos (campo). Os resultados indicaram variabilidadeentre cultivares em relação à injuria e ao desenvolvimento da planta. O rendimento de grãos nas parcelas infestadasfoi 6352,2 kgha-1 enquanto que nas parcelas sem infestação a produtividade foi 8048,05 kgha-1, o equivalente a umaredução média de 21,07%.Palavras-chave: Danos, perdas em rendimento de grãos, percevejo barriga-verde.

POTENTIAL RISK OF LOSSES IN MAIZE CAUSED BY Dichelops melacanthus (DALLAS) (HEMIPTERA: PENTATOMIDAE) IN BRAZIL

ABSTRACT: The incidence of the green belly stink bug, Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae), on maize crop in Brazil has increased with time, especially due to the continuous availability of food throughout theyear. This insect causes injury to seedlings, killing them shortly after their emergence from the soil. If the plant survives,it is possible to see areas with necrotic lesion that increase in a transverse pattern on the sheet, with perforations on the leaves or tillers (side shoots). This pest is currently one of the most important to maize, in conventional and Bt hybrids. The research compared the behavior of theses cultivars infested by the green belly stink bug, D. melacanthus. Bt and conventional maize cultivars were evaluated in a protected environment (greenhouse) and only Bt maize was evaluated at field. Evaluations based on plant development and insect injury occurred after seven days of the infestation period. The results indicated variability among cultivars related to insect infestation, measured by a visual scale for damage determination and plant development. Grain yield obtained from infested plots was 6352.2 kg ha-1 whereas in the noninfested plots was 8048.05 kg ha-1, equivalent to an average reduction of 21.07%.Keywords: Plant damage, grain losses, green belly stink bug. RISCO POTENCIAL DE PERDAS CAUSADAS POR Dichelops melacanthus (DALLAS)(HEMIPTERA: PENTATOMIDAE) EM MILHO NO BRASIL RESUMO - A incidência do percevejo barriga verde Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae) em milho no Brasil tem aumentado nos últimos anos, especialmente devido à disponibilidade de alimento o ano todo. A injuria provocada pelo inseto pode causar a morte da plântula reduzindo o número ideal de plantas na colheita. Se a planta sobrevive, é possível visualizar áreas necrosadas ou perfilhamento. A praga é atualmente uma das mais importantes do milho, tanto em cultivares convencionais como em cultivares Bt. A presente pesquisa comparou o comportamento destas cultivares em ambiente protegido (casa de vegetação) e no campo, avaliando a injuria provocada pela praga, o desenvolvimento da planta e a produtividade de grãos (campo). Os resultados indicaram variabilidade entre cultivares em relação à injuria e ao desenvolvimento da planta. O rendimento de grãos nas parcelas infestadas foi 6352,2 kgha-1 enquanto que nas parcelas sem infestação a produtividade foi 8048,05 kgha-1, o equivalente a uma redução média de 21,07%. Palavras-chave: Danos, perdas em rendimento de grãos, percevejo barriga-verde.

Pattern based optical memory in rubidium vapor

We investigated the optical transverse pattern produced by counterpropagating two waves through a rubidium vapor cell in presence of a longitudinal magnetic field. A bistable behav­ior is observed. The optical switching process between two of these patterns is carried out us­ing three different mechanisms: mechanical closing of a pump beam, modulation of a pump beam intensity and modulation of additional beam intensity. A rapid switching of less than 10 μs between patterns can be carried out with a 2 μw power beam.

NONLINEAR OPTICAL APPLICATIONS OF PHOTOREFRACTIVE LIQUID CRYSTAL LIGHT-VALVES

We show a novel nonlinear optical medium, which is formed by coupling a liquid crystal layer to a photoconductive crystal. We show that this medium allows the control of the liquid crystal birefringence in a local and dynamical way, so that large optical nonlinearities are obtained on a large transverse section. The properties of the photorefractive liquid crystal light-valves are used to implement transverse pattern formation, two-wave mixing amplification and phase conjugation.