RESUMO
Polarization switching in a long-wavelength vertical-cavity surface-emitting laser (VCSEL) under parallel optical injection is analyzed in a theoretical and experimental way. For the first time, to our knowledge, we report experimentally a state in which injection locking of the parallel polarization and excitation of the free-running orthogonal polarization of the VCSEL are simultaneously obtained. We obtain very simple analytical expressions that describe both linear polarizations. We show that the power of both linear polarizations depend linearly on the injected power in such a way that the total power emitted by the VCSEL is constant. We perform a linear stability analysis of this solution to characterize the region of parameters in which it can be observed. Our measurements qualitatively confirm the previous theoretical predictions.
RESUMO
Five Gram-negative, facultatively anaerobic, non-spore-forming, coccoid rod-shaped bacterial isolates were obtained from infant formula and an infant formula production environment and were investigated by use of a polyphasic taxonomic study. Biochemical tests and partial rpoB gene sequence analysis of the five isolates revealed that they formed two distinct groups in the family Enterobacteriaceae, closely related to several species of the genera Pantoea and Erwinia, which indicated a phylogenetic position within the genus Pantoea or the genus Erwinia. Multilocus sequence analysis of concatenated partial atpD, gyrB, infB and rpoB gene sequences of two of the isolates suggested that they represented two novel species of the genus Pantoea, phylogenetically related most closely to Pantoea septica. The five isolates had general characteristics consistent with those of the genus Pantoea, and DNA-DNA hybridizations between two representatives and the type strains of their phylogenetically closest relatives based on comparative 16S rRNA gene sequence analysis showed that the isolates represented two novel genospecies. These two genospecies could be differentiated from each other based on fermentation of galacturonate, sorbitol and potassium 5-ketogluconate. They could be differentiated from phylogenetically related Pantoea species based on their ability to ferment lactose and to utilize ß-gentiobiose and raffinose, their inability to ferment or utilize d-arabitol, and their inability to produce indole. On the basis of the results obtained, the five isolates are considered to represent two novel species of the genus Pantoea, for which the names Pantoea gaviniae sp. nov. (type strain A18/07(T) =LMG 25382(T) =DSM 22758(T)) and Pantoea calida sp. nov. (type strain 1400/07(T) =LMG 25383(T) =DSM 22759(T)) are proposed.
