Tunable Optical Metamaterials And Its Applications

Nowadays,optical methods have been increasingly applied in the field of biomedicine.Among them,a special artificial material called optical metamaterials has attracted wide attention.In this paper,the applications of different optical metamaterials in the biomedicine field are described,such as the detection of biochemical substances by its super transmission and reflection properties,or the design of optical tweezers with the function of capturing biochemical particles by its super plasmon resonance properties.However,this paper also illustrates that metamaterials have many practical limitations in these applications,including its plasmon resonance frequency is not tunable,the use is single and so on.Aiming at these limitations of metamaterials,this paper attempts to adopt new methods to design metamaterials.Firstly,this paper describes the theoretical principles involved in the design of optical metamaterials,including the principle of plasma resonance,the principle of phase transition of vanadium dioxide,and the principle of optical capture of biochemical particles.Then,this paper introduces the numerical calculation method of electromagnetic field to analyze the electromagnetic properties of metamaterials,and makes a detailed analysis of the time-domain finite difference method,including its principle,advantages and disadvantages,and how to apply it in our design.In this paper,a periodic opening structure is proposed,and the finite difference time domain method was used to analyze the electromagnetic properties of the opening structure.The phenomenon of plasma resonance is found in the transmission spectrum.After changing the geometry size of the structure,it is found that the resonant spectral line is obviously related to its geometry size.After obtaining the structure with plasmon resonance property,this paper introduces a kind of vanadium dioxide material which can change the optical property.,this material can be artificially controlled to obtain different refractive indexes,and it has been used in other optical materials.When the material is in one phase state,our structure has the strong plasma resonance,while when the phase state of the material has changed,we found that this resonance phenomenon becomes very weak.By this way,we have achieved a breakthrough in attaining tunable plasma resonance properties for a metamaterial.Finally,we applied the metamaterials with tunable electromagnetic properties to the optical tweezers.We found that when there is a strong plasma resonance,this metamaterial has a strong force to capture the biochemical particles,and after the phase transition,the force became very small,and the capture position changed.So,this metamaterial has a good breakthrough significance and practical value,and a bright future.