Analysis Of Optical Characteristics Based On Optical Fiber Integrated Metasurfaces

As a two-dimensional and easily controlled electromagnetic material,metasurfaces can be resonantly coupled with the electrical or magnetic components of the incoming electromagnetic wave,showing undiscovered properties in nature.However,most of metasurfaces have shortcomings such as difficulty in spatial alignment and lack of on-line control,which is not favorable for the development of photonic integration technology.Recently,the emergence of the ‘lab-on-fiber’ provides a powerful platform for the integration and miniaturization of devices.The researchers mainly integrate micro and nano devices inside,on the sides and on the tip of the fiber.This technology has important implications in the fields of device integration,biosensors,information processing and environmental monitoring.In this thesis,the all-dielectric phase gradient metasurface is integrated on the optical fiber tip to realize the beam deflection,and the results are in good agreement with the theory.By further enriching the emergent ‘lab-on-fiber’ framework,this may pave the way for the widespread diffusion of optical metasurfaces in real-world applications to communications,signal processing,imaging and sensing.In this work,focusing on the two most basic parameters of electromagnetic waves-amplitude and phase,it carries out researches on transmission characteristics based on fiber integrated metasurfaces.The main research work includes the following points:1.Based on the Pancharatnam-Berry phase principle,a rectangular silicon nanostructure was designed.By rotating the angle of the nano-unit structure,a phase gradient metasurfaces with different unit numbers was constructed.And analyze the effect of array period on abnormal transmission efficiency and deflection angle.The periodic structure achieves an abnormal transmission efficiency close to 90% at 1.3 μm,and the deflection angle is consistent with the theoretical value.Integrated on the fiber tip,it achieves a maximum transmission efficiency of 84% at 230 THz.The transmission efficiency of more than 50% is achieved in a wide frequency band.2.Based on the transmission phase principle,two all-dielectric arrays are designed.By changing the geometric parameters of the structure to achieve electromagnetic resonance response,and then it can achieve full phase control.For the cross-shaped structure,breaking the periodicity of the cruciform structure and changing the spacing between the structures to improve the abnormal transmission efficiency.For the cylindrical structure,the effect of the number of unit structures on the abnormal transmission efficiency and deflection angle was studied.By integrating the unit into the optical fiber tip,the maximum efficiency of 71% was achieved.