Large-area broadband optical absorber fabricated by shadowing sphere lithography.

We report a large-area broadband optical absorber consisting of Ag/SiO2 stacked plasmonic layers fabricated on a self-assembly polystyrene sphere monolayer using the glancing angle deposition. Such an absorber can absorb more than 90% of light in the spectral range of 350 - 850 nm when the polystyrene spheres have a diameter of 750 nm. The broadband absorption is due to the overlap of localized plasmonic resonance wavelengths resulting from different patchy sizes and shapes of Ag coating on polystyrene spheres. Such a simple, flexible and large-area absorber has potential applications in light cloaking and energy conversion.

Switchable reflection/transmission utilizing polarization on a plasmonic structure consisting of self-assembly polystyrene spheres with silver patches.

We report a plasmonic structure for switchable reflection and transmission by polarization. The structure is composed of a hexagonal-packed polystyrene sphere array with silver patches on them. Simulations and experiments demonstrated that the conversions between reflected beams and transmitted ones can be performed when the polarization directions of incident beams vary from 0° to 90°. A switchable reflection and transmission at a given wavelength can be obtained, as long as sizes of PS spheres and azimuthal angles are properly chosen. Such a patchy plasmonic structure serving as a switch between reflection and transmission have potential applications in photoelectric control devices.

Polarization-independent broadband plasmonic absorber based on a silicon-nanowire array decorated by gold nanoparticles at the optical regime.

We present a design for a plasmonic absorber that is composed of a hexagonal-packed silicon nanowires (SiNWs) array with gold nanoparticles (AuNPs) decoration. Simulations and experiments demonstrated that the proposed absorber achieves a broadband absorption. Its bandwidth over an absorption of 80% ranges from 400 nm to 1000 nm at 0 degree to 30 degrees incidence. It was also demonstrated that the plasmonic absorber is polarization-insensitive. Analyzing the field distributions in the structure, we find that the wideband absorption is ascribed to the formation of cavity modes in the SiNWs and surface plasmon polaritons on the AuNPs. Such a designed plasmonic structure with high-efficiency absorption can be served as a good optical absorber.

[Simultaneous quantitative analysis of three kinds of phenols by Elman recurrent neural network].

Elman recurrent neural network ( ERNN) was applied to study the simultaneous quantitative analysis of seriously overlapped spectra of a p-nitrophenol, o-nitrophenol and 2,4-dinitrophenol system. The multivariate linear regression (MLR) method was also applied in this study for comparison. Two programs (PERNN and PMLR) were designed to perform the calculations. By optimization, the structure and parameters of Elman recurrent neural network were defined. The relative standard errors of prediction (RSEP) for all components with ERNN and MLR were 3.1% and 2 027.3%, respectively. Experimental results showed the method to be successful even where there was a severe overlap of spectra. The ERNN method is a valuable tool in solving the minimum problem and improving the convergence rate, and can be used to analyze the whole spectra rather than just picking out a few characteristic values. The method provides a new way of simultaneous determination of severely overlapped molecular spectra without prior separation.