Modulation Of Optical Properties By Accumulation Electron Gas And Its Applications In Tamm Structures

Electronic devices and systems have become necessities in our daily lives.Passing through the doorsill of 21 th century,photonics has been advanced greatly,propelling photonic technology to accelerate forward to revolutionize how people to live.However,the photonic technology is still unable to satisfy people's increasing demands alone.Consequently,people have been seeking for the combination of electronic and photonic technologies.As an important research field in the combination of electronic and photonic technologies,the influence of accumulation electron gas on the optical properties of materials draws attentions of researchers globally.In this dissertation,we studied the accumulation electron gas in bulk KNSBN surface,indium tin oxide film surface and monolayer graphene and discussed the accumulation processes.The influences of accumulation electron gas on the photorefractive effect,permittivity and surface conductivity were analyzed,either experimentally or/and theoretically.The transfer matrix for an ultrathin layer was established.Moreover,we designed and simulated some optical devices by combining the accumulation electron gas with Tamm structure.Firstly,the impact of accumulation electron gas on the photorefractive effect in KNSBN crystals was investigated.We approximately calculated the surface electron density through measuring electric current density in the circuit using picoammeter.Enhancement of photorefractive phenomenon was observed through two beam coupling experiment.It is believed that a thin phase grating was responsible for the diffraction pattern with many high orders,which was also confirmed by the related reading experiment.Based on the experimental results,the mechanisms behind this enhancement was discussed and the excitation of surface plasmon polaritons was briefly analyzed.Then the effect of accumulation electron gas on the permittivity of indium tin oxide was studied.The permittivity of accumulation layer in indium tin oxide was measured through detecting the excitation of surface plasmon polaritons.An 808 nm laser was used in the experiment,which is far away from the intrinsic plasmonic wavelength of the indium tin oxide.Thus,the influence of unmodified layer can be ignored.Relations between electron relaxation time and accumulation layer's thickness was analyzed through introducing Mayadas-Shatzkes mode.As the result,accumulation electron density,accumulation layer's thickness and permittivity were connected.Therefore,the amount of the accumulation electron gas can be derived from the permittivity.In addition,the influence of applied voltage on the permittivity of accumulation layer andthe slow accumulation process.Furthermore,the influence of accumulation electron gas on the surface conductivity of monolayer graphene was investigated.The surface conductivity of monolayer graphene was derived from Kubo formula.Thus,the influence of accumulation electron gas on the surface conductivity was theoretically studied.Meanwhile,we derived the transmission matrix of ultrathin layers from Maxwell equations,finding that this transmission matrix can mitigate the calculation error stemming from the fuzzy interfaces of ultrathin layers.Using this transfer matrix method,we dealt with the optical transmission of accumulation electron gas stack structures and studied the band-stop phenomenon of these stack structures.In addition,the influences of layer's number and thickness,light's polarization and incidence angle on the transmission have been discussed.In addition,a special multi-layer structure was presented,with great band-stop phenomenon in the visible band and potential in designing electro-optical filters.Finally,we tried to combine accumulation electron gas with Tamm plasmon polaritons.Through using the strengthened electric field of Tamm plasmon polaritons,the adjusting ability of accumulation electron gas can be enhanced.We designed a tunable perfect absorber near 808 nm by introducing indium tin oxide into a Tamm structure,and discussed the influences of accumulation electron density,films' thicknesses and incident angle on the perfect absorber.Meanwhile,the self-repairing property of this perfect absorber was discussed,namely,the slight manufacture defects can be repaired by changing the electron density and the incident angle,which greatly enhances the fault tolerance of this configuration.Combining the accumulation electron gas in monolayer graphene with Tamm structure,we designed a tunable filter near 1550 nm.The influences of Bragg mirror's periods and the distance between silver film and the monolayer graphene on the filter performance was also studied.