Vectorial spin-orbital Hall effect of light upon tight focusing and its experimental observation in azopolymer films

Hall effect of light is a result of symmetry breaking in spin and/or orbital angular momentum(OAM)possessing optical system and is caused by e.g.refractive index gradient/interface between media or focusing of a spatially asymmetrical beam,similar to the electric field breaking the symmetry in spin Hall effect for electrons.The angular momentum(AM)conservation law in the ensuing asymmetric system dictates redistribution of spin and orbital angular momentum,and is manifested in spin-orbit,orbit-orbit,and orbit-spin conversions and reorganization,i.e.spin-orbit and orbit-orbit interaction.This AM restructuring in turn requires shifts of the barycenter of the electric field of light.In the present study we show,both analytically and by numerical simulation,how different electric field components are displaced upon tight focusing of an asymmetric light beam having OAM and spin.The relation between field components shifts and the AM components shifts/redistribution is presented too.Moreover,we experimentally demonstrate,for the first time,to the best of our knowledge,the spin-orbit Hall effect of light upon tight focusing in free space.This is achieved using azopolymers as a media detecting longitudinal or z component of the electrical field of light.These findings elucidate the Hall effect of light and may broaden the spectrum of its applications.

Optical multiplexing techniques and their marriage for on-chip and optical fiber communication:a review

Herein,an attention-grabbing and up-to-date review related to major multiplexing techniques is presented which in-cludes wavelength division multiplexing(WDM),polarization division multiplexing(PDM),space division multiplexing(SDM),mode division multiplexing(MDM)and orbital angular momentum multiplexing(OAMM).Multiplexing is a mech-anism by which multiple signals are combined into a shared channel used to showcase the maximum capacity of the op-tical links.However,it is critical to develop hybrid multiplexing methods to allow enhanced channel numbers.In this re-view,we have also included hybrid multiplexing techniques such as WDM-PDM,WDM-MDM and PDM-MDM.It is prob-able to attain N×M channels by utilizing N wavelengths and M guided-modes by simply utilizing hybrid WDM-MDM(de)multiplexers.To the best of our knowledge,this review paper is one of its kind which has highlighted the most prom-inent and recent signs of progress in multiplexing techniques in one place.

Thermoelectric and electrical characteristics of SmS ceramic samples after exposure to a pulsed magnetic field

Samarium monosulfide(SmS)is a promising material for creating thermoelectric generators(TEG),gas sensors and strain gauges.Despite the high values of the generated thermo electromotive force(TEMF)(α≈170-350μV/K),methods for increasing the efficiency of TEGs based on SmS are of considerable interest.One of these methods can be short-term effects of magnetic fields,including pulsed ones,on these materials.The action of a pulsed magnetic field(PMF)leading to an increase in TEMF(U)of SmS ceramic samples is found.Samples that are not subjected to high frequency currents(HFC)annealing show an increase in UT of 44.54%-62.18%(from 11.9 to 17.2-19.3 mV).The conductivity(σ)of the samples is~22 Q/cm and is insensitive to short-term exposure to a PMF.Samples that undergo HFC annealing show an increase in Uof 23.47%-41.31%(from 21.3 to 26.3-30.1 mV)after exposure to a PMF.The conductivity of the samples is~15Ω^(-1)/cm and after a short exposure to the PMF is changing nonmo notonically,with an increase in the overall instability.The difference in the values of Uand a can be explained by presence of an ordered grain structure and a significant amount of the Sm_(2)O_(2)S phase in the samples subjected to HFC annealing.Possible mechanisms of the observed changes are discussed.