Study On Metasurface Micro-Optics Lens

With the development of miniaturization and integration of optical imaging systems,traditional optical lenses are increasingly difficult to meet the needs.Due to the continuous rise of materials science,metasurface,as a metamaterial with the ability to change the phase distribution of wavefront,can introduce additional phase difference through artificial design control,so that it has the ability to realize micro-regulation of light in the subwavelength range,whitch provides a new method of light field regulation for scientific research workers.Metasurface,as a two-dimensional metamaterial,is not only small in size and easy to integrate in weight,but also has unique advantages in production and processing because its processing mode is compatible with the micronano processing technology of MOS,which is easy to achieve large-scale production.Compared with traditional lenses,which are limited by the complex processing of special surfaces,the design of metasurface lenses is more free and reflects the wavefront control ability of the metasurface with higher freedom.The main contents of this dissertation include:A strict coupled wave solver was used to parameterize the metasurface basic units.The metasurface basic units based on the transmission phase and geometric phase were obtained,respectively.The phase modulation from zero to 2π was realized,and high transmittance was ensured at the same time.By using the phase of geometric phase and transmission phase to compensate achromatic,the geometric phase is introduced by rotating the structure of nano-brick to determine the phase of the upper limit of achromatic band λmax.Aiming at the light in the middle band from λmin to λmax,the length and width of nano-brick with geometric phase are scanned under the condition of step size0.002 micron,and the unit database of compensating phase is established.The size of the structure at each position of the metallens is obtained by matching the index.Finally,achromatic treatment from 500 nm to 700 nm was realized,and an achromatic lens with focal length of 15 microns,diameter of 9 microns and numerical aperture size of 0.41 was designed.The focal length change rate of the focus is 12.55%,and the focusing efficiency in different bands is above 30%.Based on the principle of different phase modulation of left and right rotation circular-polarized light by geometric phase,two phases of convex lens and concave lens are introduced on the metasurface respectively by means of metasurface holography and space division multiplexing,so as to realize the double focus in the focal plane in the transverse direction and the double focus in the optical axis in the longitudinal direction.By changing the ellipsometry of incident light,the intensity of the two focal light can be adjusted.The focal plane of the transverse bifocal lens is 10 microns away from the lens,and the distance between the two focal points is 6 microns in the x direction.The maximum focusing efficiency of the left and right focal points can reach 25.41% and25.42%,respectively.The longitudinal bifocal lens has two focal lengths of 10 microns and 15 microns respectively,the focusing efficiency can reach 16.96 % and 19.09%respectively.And both bifocal lenses have diameters of 18.3 microns.A cubic phase Alvarez bifocal zoom lens with varying focal moment is designed based on the idea of space division multiplexing.It is designed that one focal point of the bifocal lens is fixed at 20 microns,and the other focal point can be adjusted by transverse displacement in the x direction.The numerical aperture size of fixed focus is 0.4734,and the numerical aperture size of variable focus can vary between 0.2616 and 0.6308.The future may show potential in optical tomography imaging,optical data storage,optical sensing,and optical communication.