We demonstrate a polymer slot waveguide Young interferometer coated with a bilayer of Al₂O₃/TiO₂. The approach enables relaxed dimensions of the polymer waveguide which simplifies the fabrication of the structure with a resolution of 50 nm. The layers were coated by an atomic layer deposition technique. The feasibility of the device was investigated by exploiting the interferometric structure as a bulk refractive index sensor operating at 975 nm wavelength for detection of an ethanol-water solution. A refractive index change of 1 × 10^-6 RIU with a sensing length of only 800 µm was detected. The approach confirms the possibility of realizing a low cost device with a small footprint and enhanced sensitivity by employing the TiO₂ rails in the sides of the slot waveguide.

We introduce a novel concept for an optical waveguide called a strip-loaded slot waveguide. It allows an extraordinary confinement of the field in a waveguide with an extremely tiny (vertical) cross section. Unlike conventional slot waveguides, the proposed configuration has potential for very low propagation losses. Its operation is demonstrated at telecommunication wavelengths and, in addition, it is fabricated by means of mass production compatible techniques: atomic layer deposition and nanoimprint replication. The possibility to fabricate the proposed structure with such low-cost techniques opens a new path for a variety of nanophotonics applications.

In order to investigate phase change materials (PCMs) thermal energy storage capacity as well as shape stability, PCM nanocomposites were fabricated by employing modified expanded graphite (EG) as a conductive filler and polyethylene glycol (PEG) PCM. To improve PCM composite shape stability, EG surface has been modified by utilizing Toluene 2 and 4 diisocyanate (TDI), ethylene glycol and PEG 600, respectively. Findings have illustrated that for PEG PCM/modified EG nanocomposites, shape stability was achieved at 5 wt.% of modified EG filler with less than 10% of melt leakage for all prepared samples as a consequence of surface adsorption capacity increment as well as adequate compatibility. Furthermore, phase change efficiency was calculated as 98% and in addition, thermal diffusion at PCM melting temperature range was negligible and approximately equal to zero. To conclude, it could be declared that, fabricated phase change material composite had desirable characteristics along with adequate shape stability for thermal energy storage applications.

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