Recent Advances in Photoalignment Liquid Crystal Polarization Gratings and Their Applications

Liquid crystal (LC) circular polarization gratings (PGs), also known as Pancharatnam–Berry (PB) phase deflectors, are diffractive waveplates with linearly changed optical anisotropy axes. Due to the high diffraction efficiency, polarization selectivity character, and simple fabrication process, photoalignment LC PGs have been widely studied and developed especially in polarization management and beam split. In this review paper, we analyze the physical principles, show the exposure methods and fabrication process, and present relevant promising applications in photonics and imaging optics.

Investigations of Different Liquid Based Spectrum Beam Splitters for Combined Solar Photovoltaic Thermal Systems

In the spectrum beam split approach of combined solar photovoltaic thermal system (PVT), the complete solar spectrum is splitted. The unwanted part of the solar spectrum for photovoltaic (PV) applications is filtered out and is used separately as heat. In this work, some inexpensive, clear, and easily available selective fluids are identified which can be used as both volumetric heat absorbers and selective spectrum filters for C-Si-based PVT. The electrical performance of a C-Si solar PV cell using these fluid-based filters is analyzed using a solar simulator at 1 Sun, AM 1.5 G. To check the volumetric heat absorbing potential, the required thermophysical properties of these selected fluids are estimated using a solar radiation pyranometer and standard experiments. The study concludes that water, coconut oil, and hydrotreated silicone transformer oil are some of the potential beam splitters and heat absorbers suitable for C-Si based spectrum beam split PVT applications.