Dispersion monitoring for high-speed WDM networks via two-photon absorption in a semiconductor microcavity

Due to the continued demand for bandwidth, network operators have to increase the data rates at which individual wavelengths operate at. As these data rates will exceed 100 Gbit/s in the next 5-10 years, it will be crucial to be able to monitor and compensate for the amount of chromatic dispersion encountered by individual wavelength channels. This paper will focus on the use of the novel nonlinear optical-to-electrical conversion process of two-photon absorption (TPA) for dispersion monitoring. By incorporating a specially designed semiconductor microcavity, the TPA response becomes wavelength dependent, thus allowing simultaneous channel selection and monitoring without the need for external wavelength filterin

Reduction of multiple access interference in a DS-OCDMA system via two-photon absorption

We demonstrate a technique to suppress multi-access interference in an OCDMA system by using the nonlinear process of Two-Photon Absorption. This allows the extinction ratio to be improved by 5dB when compared to linear detection

Dispersion Monitoring for High-Speed WDM Networks via Two-Photon Absorption in a Semiconductor Microcavity

ABSTRACT Due to the continued demand for bandwidth, network operators have to increase the data rates at which individual wavelengths operate at. As these data rates will exceed 100 Gbit/s in the next 5 -10 years, it will be crucial to be able to monitor and compensate for the amount of chromatic dispersion encountered by individual wavelength channels. This paper will focus on the use of the novel nonlinear optical-to-electrical conversion process of Two-Photon Absorption (TPA) for dispersion monitoring. By incorporating a specially designed semiconductor microcavity, the TPA response becomes wavelength dependent, thus allowing simultaneous channel selection and monitoring without the need for external wavelength filtering

CopC Protein from Pseudomonas fluorescens

Copper homeostasis in the bacterium Pseudomonas fluorescens SBW25 appears to be mediated mainly via chromosomal cue and cop systems. Under elevated copper levels that induce stress, the cue system is activated for expression of a P1B-type ATPase to remove excess copper from the cytosol. Under copper-limiting conditions, the cop system is activated to express two copper uptake proteins, Pf-CopCD, to import this essential nutrient. Pf-CopC is a periplasmic copper chaperone that may donate copper to the inner membrane transporter Pf-CopD for active copper importation. A database search revealed that Pf-CopC belongs to a new family of CopC proteins (designated Type B in this work) that differs significantly from the known CopC proteins of Type A that possess two separated binding sites specific for Cu(I) and Cu(II). This article reports the isolation and characterization of Pf-CopC and demonstrates that it lacks a Cu(I) binding site and possesses a novel Cu(II) site that binds Cu(II) with 100 times stronger affinity than do the Type A proteins. Presumably, this is a requirement for a copper uptake role under copper-limiting conditions. The Cu(II) site incorporates a highly conserved amino terminal copper and nickel (ATCUN) binding motif, NH2-Xxx-Xxx-His, but the anticipated ATCUN binding mode is prevented by a thermodynamically more favorable binding mode comprising His1 as a key bidentate ligand and His3 and His85 as co-ligands. However, upon His1 mutation, the ATCUN binding mode is adopted. This work demonstrates how a copper chaperone may fine tune its copper binding site to meet new challenges to its function

Environmental, Economic, and Ethical Assessment of the Treated Wastewater and Sewage Sludge Valorization in Agriculture

International audienc