RESUMO
Microstructured optical fibers (MOFs) are traditionally prepared using the stack and draw technique. In order to avoid the interfaces problems observed in chalcogenide glasses, we have developed a new casting method to prepare the chalcogenide preform. This method allows to reach optical losses around 0.4 dB/m at 1.55 µm and less than 0.05 dB/m in the mid IR. Various As(38)Se(62) chalcogenide microstructured fibers have been prepared in order to combine large non linear index of these glasses with the mode control offered by MOF structures. Small core fibers have been drawn to enhance the non linearities. In one of these, three Stokes order have been generated by Raman scattering in a suspended core MOF pumped at 1995 nm.
Assuntos
Calcogênios/química , Tecnologia de Fibra Óptica/instrumentação , Vidro/química , Desenho de Equipamento , Análise de Falha de Equipamento , Dinâmica não LinearRESUMO
The phase-matching curves for the four-wave mixing effect of Bragg scattering in two fibers with opposite sign ß(4) dispersion coefficients have been measured experimentally. The measured phase-matching curves are in good agreement with theoretical expectations, and their dependence on several key parameters has been determined.
RESUMO
Early onset torsion dystonia are rare movement disorders. Molecular defect is known for only a subgroup, consisting of a unique and recurrent mutation in the TOR1A gene. We undertook a nationwide census of French TOR1A-mutation carriers and the assessment of clinical associated signs. Overall, 53 index cases and 104 relatives were studied and haplotypes linked to the mutation constructed. The previously reported Ashkenazi-Jewish haplotype was found in 11 families with the remainder carrying distinct haplotypes suggesting independent mutation events. This study demonstrates the scarcity of this disease in France with estimated disease frequency of 0.13:100,000 and mutation frequency of 0.17:100,000.
Assuntos
Distonia Muscular Deformante/genética , Chaperonas Moleculares/genética , Deleção de Sequência , Adolescente , Idade de Início , Estudos de Casos e Controles , Criança , Feminino , França , Frequência do Gene , Ligação Genética , Haplótipos , Heterozigoto , Humanos , Judeus/genética , Masculino , FenótipoRESUMO
Efficient, wideband and tunable optical wavelength conversion over 180 nm by four-wave mixing (Bragg scattering) in a fiber is demonstrated experimentally. This process has the potential to translate optical data (states of light) without the noise pollution associated with parametric amplification and spontaneous Raman scattering.
RESUMO
We present approximate but nevertheless highly accurate self-similar solutions to the generalized linear Schrödinger Equation appropriate to the description of pulse propagation in an optical fibre under the influence of distributed dispersion and gain or attenuation. These new similariton solutions apply for any shape of linearly chirped pulse for any dispersion and gain profiles and are indistinguishable from numerically generated solutions in the majority of practical applications.