Publications by authors named "Changsong Xie"

As a typical planar 4-connected ligand that possesses symmetry, the squarate ligand is expected to construct some interesting topologies. Here, we report that the assembly of the squarate ligand with rare-earth ions can produce a series of (4, 8)-connected frameworks with the "smallest" type topology. Among these compounds, the Tb based analogue not only possesses a good proton conductivity, but also exhibits luminescence responses toward MnO and CrO, making it a candidate for multifunctional materials.

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It is a challenge to effectively load proton carriers in COFs to improve their proton conductivity. Herein, we report a series of COF-based composites, PANa@UCOF- (PANa: sodium polyacrylate, : weight percentage of PANa), which were prepared by coating different proportions of superabsorbent PANa on the COF surface based on an reaction strategy. Since PANa can greatly enhance the enrichment of water molecules in one-dimensional (1D) channels of COFs, these COF-based composites exhibit superprotonic conduction.

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This work contributes experimental demonstrations and comprehensive comparisons of various modulation and coding techniques for 200 Gb/s intensity modulation and direct detection links including four-level pulse amplitude modulation (PAM-4), PAM-6, trellis-coded modulation (TCM) over PAM and discrete multi-tone (DMT) transmission. Both C-band Mach-Zehnder modulator and O-band electro-absorption modulated laser transmitters were examined for intra-data center applications based on state-of-the-art commercial components.

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Creating novel and practical materials to separate oil/water mixtures with high efficacy is in urgent demand. Herein, we demonstrate an amphipathic pentiptycene-based copper metal-organic framework (Cu-MOF; UPC-29) to satisfy this purpose. UPC-29 exhibits a efficient separation performance for mixtures of naphtha/water, gasoline/water, and diesel/water.

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Coherent optical communication systems are still too expensive for metro and short reach networks in the near future. Coherent detection with an intensity modulator replacing a costly dual-polarization in-phase and quadrature modulator could offer a good trade-off between cost and performance for metro networks. The major performance limit of such systems is the nonlinearity.

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We experimentally demonstrate the generation and successful transmission of a single-lane 180 Gb/s (90 GBd) duo-binary four-level pulse-amplitude modulation (DB-PAM-4) signal over an 80 km standard single-mode fiber with a net data-rate of 150 Gb/s, enabled by a dual-drive Mach-Zehnder modulator-aided dispersion pre-compensation. A net data rate of 168 Gb/s is also achievable, for ranges up to 40 km. To mitigate bandwidth limitations and error spreading, pre-coded DB-PAM-4 is used; the pre-coding provides a gain of approximately 1 dB.

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We experimentally demonstrate the possibility of transmitting 112  Gb/s PAM-4 signals over 30-km standard single-mode fibers with commercial 20-GHz components. The impact on system performance of three different equalization schemes-feed-forward equalizer (FFE), Volterra filter (VF), and maximum likelihood sequence estimator (MLSE)-is investigated and compared. We prove that the |x| and x|x| components of the VF can efficiently reduce the chirp-induced signal skew distortion, and that an MLSE with only four states can be used to remove the error floor.

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Direct detection systems with advanced modulation schemes are of great importance in metropolitan networks, because of their low cost and low power requirements. In particular, PAM-4 has attracted considerable attention, but has significant transmission distance limitations in the C-band. To extend its reach, we used a dual drive Mach-Zehnder modulator to generate a chromatic dispersion (CD) pre-compensated signal with an extra (j-1) multiplication to align the optical carrier and the modulated optical signal; by doing so, we achieved successful 128 Gbit/s transmission over an 80 km SSMF link, the longest reported reach of single lane 100 Gbit/s PAM-4 signals over DCF-free links.

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We experimentally demonstrate the generation and transmission of a single-lane 180  Gbit/s (90 GBaud) four-level pulse-amplitude modulation (PAM-4) signal in an intensity-modulation direct-detection system with a 7.5 GHz 3 dB bandwidth. The generated signal is transmitted over a 2 km standard single-mode fiber with, to the best of our knowledge, the highest reported net data rate in the C-band: 150  Gbit/s.

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Synopsis of recent research by authors named "Changsong Xie"

  • - Changsong Xie's research primarily focuses on the development of novel materials and systems for applications in proton conduction, oil/water separation, and high-speed optical communication, demonstrating a versatile approach to materials science and engineering.
  • - Recent findings include the creation of rare-earth squarate frameworks that exhibit exceptional proton conductivity and luminescence responsiveness, as well as composites made from covalent organic frameworks that significantly enhance water uptake and proton conduction.
  • - In the field of optical communication, Xie's work has advanced modulation formats for high-speed data transmission, successfully demonstrating the use of PAM-4 signaling for 180 Gb/s data rates over conventional optical fibers and addressing challenges related to system performance and nonlinearity mitigation.