In this work, an ultra-long single-span 10Gbps SDH optical communication system was built up and tested. The 10G signal transmitted from the bit error tester with an additional 10G XFP transponder module, and looped back to the bit error tester. All the conditions and results presented were verified as error-free for over 12h. The 10G XFP module was used to perform an optical-electric-optical (OEO) conversion, so that the modulation parameters can be adjusted for nonlinearity optimization, which will be discussed elsewhere. The total distance of the fiber is over 220km, and the maximum power of the signal injected into fiber is over 17dBm, indicating that the SBS threshold is suppressed over 17dBm with the help of the 10G XFP optimization. What is interesting is, a clear wide shoulder was observed in the output signal spectrum at the transmission fiber output, provided that the fiber input power exceeds 17dBm. After careful analysis and simulation, we attributed this shoulder generation to the intra-band FWM effect, which is caused due to the FWM interaction between the carrier wave and the modulation wave within the band. The error tester will identify the shoulder as the noise level, and the maximum input power is restrained by equivalent optical signal noise ratio (OSNR) due to the intra-band FWM effect. So that the maximum transmission distance will be restricted even if the stimulated Brillouine scattering (SBS) threshold can be further enhanced. Other nonlinear effects including self-phase modulation (SPM), and group velocity dispersion (GVD) are also analyzed.
ZnS thin film has wide applications in optoelectronics area, including photocatalysis and solar cells. The water bath is a popular ZnS thin film fabrication method, with merits of high efficiency, easy-operation, low cost, and uniform deposition. In this report, ZnSO47H2O and thiourea were mixed in the water bath for reaction at a constant temperature with mechanical stirring. Thus-deposited ZnS thin film was then annealed in Ar. The impacts of different pH, different concentration, different water bath temperature, and different annealing temperature and time were studied to find the optimal condition. The optimal results were as follows: the mixture of 0.056mol/L thiourea and 0.0532mol/L ZnSO47H2O in water was titrated to pH=10.7 by ammonia, followed by water bath reaction at 85°C, then annealed in Ar at 300°C for 1.5h. Thus fabricated ZnS thin film has the best surface flatness and film uniformity, with high optical transmittance.
The silver nanoparticle (AgNP) based conducting wire is a fundamental element of flexible electronic devices, especially in the printing electronics area. Its resistance change mechanisms under pressure is of both scientific interest and practical importance. AgNP-based conducting wires were fabricated on flexible substrates by electrospraying printing technology, and three possible resistance change mechanisms were studied: vertical deformation (VD) of the AgNP wire due to vertical pressure, horizontal wire elongation (HWE) along with the flexible substrate due to vertical pressure, and local micro deformation (LMD) at the touching edge. Analysis of the experiment data revealed that the resistance change due to VD was negligible, the resistance change due to PWE was one order of magnitude smaller than the measured value, and the resistance change due to PWE was the dominating mechanism.
Acrylic (PMMA) possesses excellent optical transparency, good chemical stability as well as many other merits such as the feasibilities in dyeing and manufacturing. But its poor hardness and wear resistance restrict its industrialized applications. In order to improve the hardness and wear resistance, SiO2 films were coated on PMMA substrates by both dip coating method and aerosol spraying method in this work. Heating curing method was carried out after the coating of SiO2 film, and consequently, the mechanical properties, optical properties and surface morphology were characterized and compared. The experimental results showed that the SiO2 films prepared by aerosol spraying method has a better performance in both hardness and wear resistance, compared with the films prepared by dip coating method. In the optimized conditions, the hardness of the PMMA was improved from 3H to ~8H, and the non-abrasion rubbing times increased from less than 100 times to 5000 times with a loading of 500g weight after the coating of SiO2 film, indicating the improvement of the wear resistance.