Distributed OTDR-interferometric sensing network with identical ultra-weak fiber Bragg gratings.

We demonstrate a distributed sensing network with 500 identical ultra-weak fiber Bragg gratings (uwFBGs) in an equal separation of 2m using balanced Michelson interferometer of the phase sensitive optical time domain reflectometry (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response and location information can be directly obtained at the same time by using the passive 3 × 3 coupler demodulation. Lab experiments on detecting sound waves in water tank are carried out.

[Spectroscopic studies on electrostatically self-assembled gold nanoparticulate thin films].

Colloidal gold was prepared by citrate-induced reduction of hydrogen tetrachloroaurate. Gold nanoparticulate thin films were built up using the electrostatic self-assembly technique and characterized by different spectroscopes. The UV-Vis absorbance spectrum indicated that the gold colloid was a monodisperse suspension.