The suppression of polarization cross talk in lead zirconate titanate phase modulators as a key error source has been challenging for open-loop fiber optic gyroscopes(FOGs).We developed a polarization-diversity optica...The suppression of polarization cross talk in lead zirconate titanate phase modulators as a key error source has been challenging for open-loop fiber optic gyroscopes(FOGs).We developed a polarization-diversity optical frequency domain reflectometry(OFDR)to measure the distributed modulation polarization error in the modulator.The error contributes 8×10^(−6) rad to FOG’s bias instability.Using a UV-fabricated in-fiberλ/4 wave plate and polarization-mode converter with fiber taper technology,the modulation error has been suppressed by 15 dB in assembled FOGs.This approach reduced error with temperature from 25°/h to 0.7°/h,meeting the requirements of control-level gyroscopes with bias errors less than 1°/h.展开更多
To improve the dispersibility of carbon nanotubes （CNTs）, poly（vinylferrocene-co-styrene） （poly （Vf-co-St））, was grafted onto the surface of CNTs by a ligand-exchange reaction. Poly（Vf-co-St） was obtained by...To improve the dispersibility of carbon nanotubes （CNTs）, poly（vinylferrocene-co-styrene） （poly （Vf-co-St））, was grafted onto the surface of CNTs by a ligand-exchange reaction. Poly（Vf-co-St） was obtained by a radical copolymerization reaction using styrene and vinylferrocene as the monomers. The vinylferrocene was synthesized from ferrocene via a Friedel-Crafts acylation. The molecular weight, molecular weight distribution, and amount of Vf in the poly（Vf-co-St） were 1.32 × 104, 1.69 and 17.6% respectively. The degree of grafting of the copolymer onto the CNTs surface was calculated from thermogravimetric analysis and varied from 27.1% to 79.7%. The addition of the poly（Vf-co-St） greatly promoted the dispersibility of the modified CNTs in anhydrous alcohol. The electrical conductivity of compo- sites prepared from the polymer-grafted CNTs and copolymer （acrylonitrile, 1,3-butadiene and styrene, ABS） strongly depended on the degree of grafting. These results show that the amount of polymer grafted onto the surface of CNTs can be controlled and that the electrical properties of composites prepared with these grafted polymers can be tuned.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61975166,62322510,and 62375223).
文摘The suppression of polarization cross talk in lead zirconate titanate phase modulators as a key error source has been challenging for open-loop fiber optic gyroscopes(FOGs).We developed a polarization-diversity optical frequency domain reflectometry(OFDR)to measure the distributed modulation polarization error in the modulator.The error contributes 8×10^(−6) rad to FOG’s bias instability.Using a UV-fabricated in-fiberλ/4 wave plate and polarization-mode converter with fiber taper technology,the modulation error has been suppressed by 15 dB in assembled FOGs.This approach reduced error with temperature from 25°/h to 0.7°/h,meeting the requirements of control-level gyroscopes with bias errors less than 1°/h.
文摘To improve the dispersibility of carbon nanotubes （CNTs）, poly（vinylferrocene-co-styrene） （poly （Vf-co-St））, was grafted onto the surface of CNTs by a ligand-exchange reaction. Poly（Vf-co-St） was obtained by a radical copolymerization reaction using styrene and vinylferrocene as the monomers. The vinylferrocene was synthesized from ferrocene via a Friedel-Crafts acylation. The molecular weight, molecular weight distribution, and amount of Vf in the poly（Vf-co-St） were 1.32 × 104, 1.69 and 17.6% respectively. The degree of grafting of the copolymer onto the CNTs surface was calculated from thermogravimetric analysis and varied from 27.1% to 79.7%. The addition of the poly（Vf-co-St） greatly promoted the dispersibility of the modified CNTs in anhydrous alcohol. The electrical conductivity of compo- sites prepared from the polymer-grafted CNTs and copolymer （acrylonitrile, 1,3-butadiene and styrene, ABS） strongly depended on the degree of grafting. These results show that the amount of polymer grafted onto the surface of CNTs can be controlled and that the electrical properties of composites prepared with these grafted polymers can be tuned.
