Investigation Of Reflective Focusing Lens Baesd On Metasurface

With the continuous advancement of semiconductor technology,optoelectronic integrated systems have developed rapidly.Optical devices are part of optoelectronic integrated systems,and their miniaturization affects the integration of the entire optoelectronic system.As the main manufacturing method of optoelectronic integrated devices,lithography directly affects the miniaturization and light weight of optoelectronic systems.How to improve the lithography resolution is a hot issue in today’s scientific research.In recent years,metasurfaces,an artificially fabricated subwavelength layered structure,have been demonstrated to achieve super-resolution imaging.As a two-dimensional planar structure,metasurface has the characteristics of ultra-light,ultra-thin,and easy-to-integration,which can directly realize the miniaturization of planar optical devices,so that optical devices can be better integrated into optoelectronic systems.Focusing lens is an important component of optoelectronic integration a nd lithography system,and its size and resolution directly affect the integration and resolution of the system.In this thesis,focusing lenses are studied based on reflective metamaterials.The main contents include the following aspects:1.A complex-amplitude-modulated reflective plasmonic super-oscillatory lens is designed,and the phase and amplitude are regulated by changing the rotating angle of nanobricks.According to the relevant parameters of the preset focal spot,such as the size of the central focal spot,side lobe intensity,etc.a single-target,multi-constraint model is established.The radial complex amplitude distribution of the device was optimized by genetic algorithm,and the full-mode structure of the reflective metasurface was constructed according to the light field response of the subwavelength structure under linearly polarized light.The constructed device is calculated by electromagnetic simulation,and the central focal spot size along the x and y directions on the preset focal plane is 253.3 nm and 271.5 nm,respectively,corresponding to0.666 and 0.714 times the diffraction limit.2.Based on the modulation principle of geometric phase,the binary phase and four-step-phase broadband achromatic focusing metasurface lenses are d esigned.The output light field realizes achromatic focusing in the form of an optical needle,and the depth of focus on the needle is controllable.According to the preset performance parameters of the optical needles,the phase distribution required by t he light field is optimized through the establishment of a reverse optimization model.Using the light field response of the subwavelength structure under circularly polarized light,a broadband achromatic focusing metasurface lens with a working bandwidth of 592.8nm to 692.8 nm was constructed.The increase of the step of phase can effectively extend the depth of focus and the depth of focus.In addition,the lens based on modulation of binary phase is polarization-independent,which can bring more flexibility and convenience to the adjustment of the light field.