By the volume integral equation method, the metal-coated dielectric probes of tilted conical shape were investigated for nanofocusing of surface plasmon polaritons (SPPs). We consider the cases of incident radially polarized (RP) and linearly polarized (LP) Gaussian beams and found that the tilted SPP conical probe is valid for both incident linearly and RP beams. Compared to the other asymmetric structures reported so far that are valid for incident LP waves, the structure proposed in this paper is not only simple but also straightforward to obtain the nanofocused localized and enhanced optical field on the tip of incident LP beam.

In this work, the mixture of red mud slurry and inorganic salt ((NH4)2SO4) has been used as an electrolyte for electrochemical activation of graphite. The red mud-activated graphite composite was then used as an adsorbent for removing methylene blue from aqueous solution by the batch method. The effect of pH, contact time, adsorbent dosage, and the initial concentration of methylene blue was investigated. The optimal condition was found at pH 6, contact time 120 min, and amount of adsorbent 1 mg/L. The maximum adsorption capacity was found to be 89.28 mg/g based on the Langmuir isotherm equation, suggesting that the red mud-activated graphite composite is a very potential adsorbent for removing methylene blue and is also used in other coloured wastewater treatments.

This paper aims to numerically propose a modern light power divider, operating at optical communication wavelength. , having unique feature on equality of two throughputs with asymmetrical structure. As a result, the divider has high potential for integrating into high-density optical circuits. Based on the analysis of dispersion and calculation of wave-vector of electromagnetic fields, we produce a simple configuration, comprising two defect points, one defect line, and one reflex mirror, for equally dividing light power inside the asymmetrical divider. Simulated results by the Finite-Difference Time Domain (FDTD) method show a good performance with transmittance of over 98% for both TE and TM waves.

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