| Modern science has been developing fast with rapid evolution of information technology.And miniaturization,high-speed and high integration of semiconductor devices have become a tendency.The development of photonics and electronics has greatly promoted the ability to process and disseminate data in the information society.Limited by the diffraction limit,traditional dielectric integrated optical devices have been hindered in the development of miniaturization and integration.In order to overcome the diffraction limit,researchers are tirelessly exploring new methods to obtain smaller,faster and more efficient photonic device so that light generation,transmission,processing,modulation,etc.can be realized in a smaller size.Surface plasmon polaritons(SPPs)are special surface electromagnetic waves,existing on the dielectric-metal surface,and SPPs are generated by the interaction between excitation photons and electrons those are free to oscillate on the metal surface.The electromagnetic wave capability exponentially decays due to dielectric losses in the direction perpendicular to the metal surface.Since the surface plasmon polaritons have a strong surface binding property,it can break through the diffraction limit.Surface plasmons polaritons have the ability to transmit light over sub-wavelength scales,which makes it possible to shrink the size of SPPs device to nanometer level through a special waveguide structure design.It is hoped that the development of integrated circuit optics will be further pushed to higher peak through research.The terahertz(THz)wave is between the far-infrared light and the microwave.It is a field of transition from electronics to photonics.It has the advantages of microwave communication and optical communication,and it also exhibits unique characteristics in transmission.Terahertz technology can be widely used in many fields,such as remote sensing,radar,national security,atmospheric and environmental monitoring,high-secure data communication,real-time extraction of biological information and medical diagnosis,etc.Therefore,research in the field of terahertz has important economic value.With the development of optics in the field of terahertz,optical devices used in the field of terahertz have become a research hotspot.This paper mainly studies the phenomenon of surface plasmons polaritons propagating along a gradient structure based on semiconductor materials in the terahertz field,which shows better SPPs performance than that on metal at low frequencies(such as microwave,midinfrared and terahertz).Moreover,the dispersion characteristics of the gradient corrugated grating waveguide are characterized by computer simulation technology(CST).In addition,the propagation characteristics of the semiconductor grating structure are analyzed in detail through the dispersion curve,2D electric field distribution,propagation loss and SPPs lifetime.The results showed that the semiconductor gradient corrugated grating waveguide can not only achieve light trapping,but also the lifetime of its plasma model is much longer than that of metal model.This paper also studies the special properties of how to release SPPs in the terahertz band.The utilization of property that the carrier concentration of In Sb can be flexibly tuned by changing temperature or doping which can achieve light trapping and release through covering a metal grating with the thermo-optic effect dielectric material or inserting a dielectric material into a metal bath.In addition,we have also realized light release in designed semiconductor gradient grating structures.By tuning the temperature,the dispersion relationship can be adjusted accordingly,so that the trapping light can be trapped tightly or released in advance.The ability to tuning dispersion properties and the confinement of electromagnetic waves could enable applications,such as optical buffers,data synchronizers,broadband slow-light systems,integrated optical filters,wavelengthdivision multiplexing and other future on-a-chip optical communications. |
PDF Full Text Request