The Study On Properties Of Photonic Nanojets Based On Gradient Refractive Index Materials

Due to the optical trap and micro-manipulation have high precision,non-contact,and no damage,make it in biology,physics,chemistry,medicine and other fields having been widely used.In micro-and nano-photonics micromanipulation,much attention has been paid to the interaction between light and matter.The process not only conveys information,but also is accompanied by the interference,scattering effect,and the conversion of energy and momentum.So it will appear that optical mechanical effects and photonic nanojets phenomenon.Researching its physical nature,is of great significance for the practical application of optical manipulation process.In this paper,the regulation of photonic nanojets and interaction between circular Airy beam and Mie particles are carried out,its main content is as follow:1.Tunable photonic nanojet phenomenon based on generalized Luneburg lens(GLLs),is engineered and achieved.Nanojet has been emerging as an interesting topic in variety photonics applications.In this paper,inspired by the properties of GLLs,firstly a two-dimensional photonic nanojet system has been developed,which focal distance can be tuned by engineering the refractive index profile of GLLs.Then a corresponding three-dimensional simulation,and structure from the continuous structure to the corresponding discretization of the photonic crystal structure are discussed.Simulation and analysis results show that the maximum light intensity,transverse and longitudinal dimensions of the photonic nanojet are dependent on the focal distance of the GLLs.Thereby,by simply varying the focal distance,it is possible to obtain localized photon fluxes with different power characteristics and spatial dimensions.So it could choose the corresponding optimized parameters according to specific application examples.This can be of interest for many promising applications,such as high-resolution optical detection,optical manipulation,technology of direct-write nano-patterning nano-lithography and so on.2.It is shown that optical force characteristic research is using circular Airy beam acting on Mie particles.Circular Airy beam is first introduced into the PNJs research field.Circular Airy beam with abruptly autofocusing properties and greater intensity gradient,which can produce large enough optical gradient force,will have a significant advantage in the field of trapping and manipulating particles.At the same time,it is convenient for abruptly autofocusing circular Airy beam in the experimental process,because regulating the beam parameters can directly adjust focusing performance.So in this paper,by the finite difference time domain(FDTD)simulation method the optical force characteristics are studied with the circular Airy beam acting on Mie particles,filling the blank in the research of the theory mechanism,and providing theory support for the corresponding more systematic experimental research.