10 Gbit/s, 300 km repeaterless transmission with SBS suppression bythe use of the RZ format

The authors have confirmed experimentally that employing the RZ format instead of the NRZ format increases the SBS threshold by ~3 dB. By using the RZ format, we have successfully conducted 10 Gbit's repeaterless transmission through 300 km of DSF. This is the longest repeaterless transmission at 10 Gbit/s ever reported     

Novel modulation and detection for bandwidth-reduced RZ formats using duobinary-mode splitting in wideband PSK/ASK conversion

This paper proposes a novel duobinary-mode-splitting scheme that uses wideband phase-shift-keying (PSK)/amplitude-shift-keying (ASK) conversion for modulation and detection of bandwidth-reduced return-to-zero (RZ) modulation formats. We have first demonstrated that the proposed scheme greatly simplifies the modulation process of the duobinary carrier-suppressed RZ format (DCS-RZ) based on baseband binary nonreturn-to-zero (NRZ) modulation. We also proposed carrier-suppressed RZ differential-phase-shift-keying format (CS-RZ DPSK) as a novel bandwidth-reduced RZ format by applying the proposed scheme in the detection process. These novel RZ formats are shown to be very useful for dense wavelength-division multiplexed (DWDM) transport systems using high-speed channels, over 40 Gb/s, with spectrum efficiencies higher than 0.4 b/s/Hz. We demonstrate that the proposed modulation and detection scheme greatly simplifies the DWDM transmitter and receiver configuration if the periodicity of the optical PSK/ASK conversion filter equals the WDM channel spacing. The large tolerance of the formats against several fiber nonlinearities and their wide dispersion tolerance characteristics are tested at the channel rate of 43 Gb/s with 100-GHz spacing. The novel CS-RZ DPSK format offers higher nonlinearity tolerance against cross-phase modulation than does the DCS-RZ format.     

Syntheses and physical properties of pyrochlore-type A2B2O7 (A=Tl,Y; B=Cr,Mn)

Pyrochlore-type A₂B₂O₇ (A=Tl,Y; B=Cr,Mn) were synthesized under conditions of elevated temperature and pressure up to 1100°C and 9GPa. Magnetic measurements indicate that the transition metals in the compounds are tetravalent and Tl₂Mn₂O₇ is ferromagnetic with the Curie temperature at 117K. Electric measurements show that Tl₂Mn₂O₇ is a semiconductor with a resistivity maximum at temperatures near the magnetic transition point but other compounds possess high resistivity of the order of 10⁸Ω·cm.     

Anomalous Grain Growth in PLZT Ceramics

The isothermal grain growth of PLZT ceramics with various La concentrations from 0 to 10 at. % is studied. For all La concentrations, the sintering time (t) dependence of grain size (D) is expressed in the normal grain growth formula, Dⁿ= Kt. The constants n and K greatly depend on the La contents. These facts indicate that there are several grain growth mechanisms related to the La concentrations in PLZT ceramics.     

Thermal expansion of ZrP2O7 and related solid solutions

The effect of solute ions on the thermal expansion of ZrP₂O₇ solid solutions was studied. The abrupt thermal expansion at the high-low inversion can be interpreted as due to the rotation of the polyhedra from the low-temperature form in the partially collapsed state to the high-temperature form in the fully expanded state. The replacement of zirconium ions by larger ions and/or the stuffing of cations into the cavities of the framework stabilized the expanded structure, and then depressed the abruptness of the expansion. Consequently the thermal expansion was reduced in Ce _x Zr_1-x P₂O₇ or (Li, Y) _x Zr_1-x P₂O₇ solid solutions.     

Nature of the prismatic dark interstitial material in Portland cement clinker

The prismatic dark interstitial material in Portland cement clinker is essentially identical with the stable solid solution phase in the system C₃A-NC₈A₃; with rapid cooling, however, metastable extension of the solid solution series takes place, which is the prevailing mechanism of formation of the prismatic phase in works clinkers of low alkali content. The presence of SiO₂ in the interstitial material favors the metastable formation by enhancing the supercooling of the liquid phase in clinker.