Influence of recording conditions on crossed-beam photorefractive gratings in doubly doped LiNbO3 crystals

The influence of the recording conditions, including the widths of the recording beams, the width ratio of the recording beams, and the recording angles, on the properties of crossed-beam photorefractive gratings in doubly doped LiNbO3 crystals is studied. A theoretical model that combines the band transport model with two-dimensional coupled-wave theory is proposed. The numerical calculations of the space-charge field, the intensity profiles of the diffracted beam, and the diffraction efficiency are presented. (C) 2006 Optical Society of America.

Effect of recording conditions on the anisotropic diffraction of volume holographic gratings

The anisotropic Bragg diffraction of the volume holographic gratings in photorefractive crystals are investigated based on the model of anisotropic coupled-wave theory. The effect of the initial intensity ratio and the recording angles of the two recording waves on the anisotropic Bragg diffraction properties is discussed. It is shown that both the ratio of the initial intensity and the incident angles of the recording waves are selective action for the anisotropic Bragg diffraction efficiency of the volume holographic gratings, while these two recording conditions are not selective action for the isotropic Bragg diffraction. Furthermore, the Bragg phase matching condition of anisotropic diffraction is analyzed when the recording angles change. (C) 2006 Elsevier GmbH. All rights reserved.

Theoretical research on noncollinear match conditions of the type I optical parametric process

Broad bandwidth group match conditions are reported for a noncollinear type I optical parametric process. The theoretical calculations corresponding to two special situations in practice were made, respectively, which are in accordance with the published experimental results. Furthermore, we provide a method to not only achieve maximal parametric bandwidth output but also match the group velocities between three waves. (c) 2006 Optical Society of America.

Effect of the A cation size disorder and synthesis conditions on the properties of an iron perovskite series

Póster presentado en The Energy and Materials Research Conference - EMR2015 celebrado en Madrid (España) entre el 25-27 de febrero de 2015

Female slave narratives: consistency and permanence: a study of two texts from the XIXth and XXth centuries

Esta dissertação tem por objetivo investigar o papel das slave narratives como poderoso gênero literário na denúncia da escravidão africana e na representação do homem negro e da mulher negra nos séculos dezoito e dezenove. Este trabalho também se propõe a investigar o papel das neo-slave narratives no estudo do passado e a representação da identidade negra no século vinte. Ambos os gêneros desafiam seus tempos presentes ao discutirem questões de etnia e subjugação humana, em uma abordagem crítica. Em Incidents in the Life of a Slave Girl (1861), Harriet Jacobs narra sua experiência na escravidão, deixando um importante legado não somente para a História mas também para a Literatura Afro-Americana. Em Dessa Rose (1986), Sherley Anne Williams, revisa o passado para resgatar a memória da escravidão e reescrever a história para examinar seu tempo presente. Além disso, as duas autoras apresentam questões de gênero, levantando questões feministas em suas obras

Beam conditions for radiation generated by an electromagnetic J 0-correlated Schell-model source

Based on the 2 x 2 (electric field) cross-spectral density matrix, a model for an electromagnetic J(0)-correlated Schell-model beam is given that is a generalization of the scalar J(0)-correlated Schell-model beam. The conditions that the matrix for the source to generate an electromagnetic J(0)-correlated Schell-model beam are obtained. The condition for the source to generate a scalar J(0)-correlated Schell-model beam can be considered as a special case. (C) 2008 Optical Society of America