We report the orthogonal tributary channel exchange of a polarization-multiplexed (pol-muxed) differential phase-shift keying (DPSK) optical time-division multiplexed (OTDM) signal by exploiting the Kerr effect-induced nonlinear birefringence in a highly nonlinear fiber (HNLF). We first implement Kerr effect-based 40-to-10, 80-to-10, and 160-to-10 Gbit/s demultiplexing of DPSK OTDM signals with power penalties of less than 0.5, 1.5, and 2.6 dB, respectively, at a bit-error rate (BER) of 10(-9). We further demonstrate 10-Gbit/s tributary channel exchange between two orthogonal polarizations of a 160-Gbit/s pol-muxed DPSK OTDM signal with a power penalty of less than 4 dB at a BER of 10(-9). Moreover, Jones matrix analyses are applied to the orthogonal polarization exchange, indicating the exchange condition of orthogonal polarization exchange with the characteristic of transparency to the modulation format. The exchange performance is analyzed in terms of the extinction ratio (ER) of the newly converted signal to the original residual signal. The dynamic range of the product of nonlinear coefficient, pump power, and effective fiber length, the dynamic range of pump power, the impact and tolerance of pump polarization offset are discussed to characterize and optimize the performance of orthogonal polarization exchange.
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http://dx.doi.org/10.1364/OE.18.016995 | DOI Listing |
As a low-energy method to increase the data rate of optical links in data centers, we propose self-homodyne Nyquist optical time division multiplexing (OTDM). In Nyquist OTDM, spectrally efficient high-baud rate signals can be generated exceeding the limit of electronic signal processing. However, full integration of OTDM systems has not been reported, mainly because of the complicated signal detection scheme, which involves demultiplexing and clock recovery.
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North China University of Water Resources and Electric Power, Zhengzhou 450046, China.
The ecology of watersheds plays an important role in regulating regional climate and human activities. The sediment-soil system in the middle and lower reaches of the Yellow River Basin (Henan section) was explored. The spatial distribution characteristics of heavy metals (HMs) showed that tributaries, which are affected by anthropogenic activities, contain higher concentrations of HMs than the main channel.
View Article and Find Full Text PDFJ Environ Manage
January 2025
School of Earth and Environmental Sciences, University of Cardiff, Cardiff, UK. Electronic address:
Insects
January 2025
Program in Ecology and Environmental Science and Large River Studies Center, Department of Biology, Winona State University, Winona, MN 55987, USA.
Prior to implementing watershed-wide projects to reduce the impacts of agriculture on regional streams and rivers, stream habitats and benthic aquatic macroinvertebrate communities were assessed at 15 sites on the South Branch Root River and its major tributaries in southeastern Minnesota, USA. Triplicate kick-net samples were collected from each site during three time periods (1998, 1999, 2006/2008) and stream habitats were inventoried within 150 m long sections at each site. In total, 26,760 invertebrates representing 84 taxa were collected and used to rate stream sites using a regional multi-metric benthic index of biotic integrity (BIBI).
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Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
Russia's invasion of Ukraine continues to have a devastating effect on the well-being of Ukrainians and their environment. We evaluated a major environmental hazard caused by the war: the potential for groundwater contamination in proximity to the Zaporizhzhia Nuclear Power Plant (NPP). We quantified groundwater vulnerability with the DRASTIC index, which was originally developed by the United States Environmental Protection Agency and has been used at various locations worldwide to assess relative pollution potential.
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