RESUMO
We have fabricated modules of 8-channel multi-wavelength lasers (MWLs) with a wavelength separation of 200 GHz for the wavelength division multiplexed-passive optical network (WDM-PON) optical line terminal sources. The variation in the output power is minimized by inserting silicone between the superluminescent diode (SLD) and the silica waveguide. The wavelength shift of each channel is less than 0.21 nm from the ITU grid and can be controlled in the range of 0.36 nm without any reductions of the output power by a tuning heater. MWLs operated successfully in the direct modulation for 1.25 Gbit/s transmissions over 20 km.
Assuntos
Lasers , Iluminação/instrumentação , Processamento de Sinais Assistido por Computador , Telecomunicações/instrumentação , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Micro-Ondas , Reprodutibilidade dos Testes , Semicondutores , Sensibilidade e EspecificidadeRESUMO
A practical optical backplane system was prepared with transmitter-receiver processing boards and an optical backplane made from polymeric-waveguide-embedded optical printed-circuit boards. Optical slots were used as connection components between the transmitter-receiver processing boards and the backplane board to permit easy and repeatable insertion and extraction of the boards with micrometer precision. We report 10 Gbit/s data transmission between an optical backplane and the transmitter-receiver processing boards.
RESUMO
An extracellular levanbiohydrolase gene, levM, from Microbacterium laevaniformans ATCC 15953 was cloned and its nucleotide sequence was determined. Nucleotide sequence analysis of this gene revealed a 1863 bp open reading frame coding for a protein of 621 amino acids. The deduced amino acid sequence of the levM gene exhibited 28-47% sequence identities with levanases, levanfructotransferases, and inulinases. The LevM was overexpressed by using a T7 promoter in Escherichia coli BL21 (DE3) and purified 24-fold from culture supernatant. The molecular weight of this enzyme was 68,800 Da based on the sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimum pH and temperature of this enzyme for levan degradation was pH 6.0 and 30 degrees C, respectively. Thin-layer and high-performance liquid chromatography analyses proved that the enzyme produced mostly levanbiose from levan in an exo-acting manner. The recombinant enzyme also hydrolyzed inulin, 1-kestose, and nystose, indicating that the enzyme cleaves not only beta-2,6-linkage of levan but also beta-2,1-linkage of fructooligosaccharides. This is the first report on a gene encoding a levanbiohydrolase that produces levanbiose as a major degradation product.
