摘要
利用超表面能够精确地控制入射光场的相位、偏振、振幅等参数,因此,超表面在量子态片上实验平台的研究过程中具有非常重要的应用前景.本文提出了一种利用超表面进行相位调控,从而产生空心光环,用以存储冷分子的方案,并通过理论研究,确定了环形结构参数,以及在焦平面上环形光场的强度分布,且计算出了环形光场捕获碘(Iodine I2)分子时产生的光学势和偶极力.研究结果表明,基于超表面单元结构设计的空心光学存储环,I2分子的最大偶极力约2.9×10-20N,比I2分子的重力大7×103倍,因此,能够满足捕获I2分子的要求,从而实现光学存储.
Abstract
The design and application of metasurface is one of the hot spots in the field of optics in recent years,and it is also an interdisciplinary research field involving physics,materials,optics,quantum information and other directions.Metasurface can precisely control the phase,polarization,amplitude and other parameters of incident light field.Therefore,metasurface has a very important application prospect in the research process of experimental platform on quantum state slices.Based on the propagation phase theory and the effective medium theory,we designed a cylindrical three-dimensional metasurface phase.Blue-detuned optical was used as incident light to form a focused hollow beam to store cold Iodine(I2)molecules.To deter-mine the parameters of the periodic structural element and the metasurface by finite element analysis software.Calculate the opti-cal field intensity of the hollow ring,and calculate the dipole potential depth,dipole force of I2 molecules in the optical field,thus proving that the designed metasurface can trap the I2 molecules.Firstly,silicon dioxide(SiO2)with a periodic width of 110 nm was selected as the substrate,and silicon(Si)column as the peri-odic structure element on the substrate.By finite element analysis,the height range of 100 nm～150 nm silicon column was scanned to find the height value of silicon column with high transmittance and phase coverage in the range of-π～π.Then,the height value of silicon column was determined to be 132 nm.Secondly,the duty cycle of silicon column within a periodic is scanned,ranging from 10%～90%,and then the functional relationship between phase value and duty cycle is obtained.Map the phase values greater than π or less than-π to the range from-π～π.Thirdly,81 periodic structural elements are arranged in the two-dimensional direction,the total width is 8.855 μm,and the discrete phase values required by these positions are determined by the functional relationship between phase value and duty cycle,so as to determine the width of silicon column of periodic structure ele-ments at different positions,forming two-dimensional unit structure array,so that the incident light converges to the focal point.The expected focal length is 5.5 μm.Finally,By adding 1.045 μm SiO2 substrate with no structure element,the total length of the 2-dimen-sional array of structued element is 9.9 μm.The end of the unstructured element is taken as the center of the circle,and a three-dimensional metasurface ring array is formed by rotating one circle.When radially polarized light with wavelength of 300 nm is inci-dent from the direction of the substrate,hollow rings are formed at the focal plane,and the expected radius is 5.445 μm.When the incident light passes through the structure elements array,it is converged into a focused hollow beam.The actual focus is 5.6 μm,and the error is 1.8%.At the focal plane,the radius is 5.438 μm,and the error is 0.13%.The width of the hollow ring is 0.54 μm,the maximum light intensity of the hollow ring increased by 39.2 times compared with the minimum light intensity.The maximum dipole potential depth of I2 molecule was about 340 μK,and the maximum dipole force was about 2.9×10-20 N.The three-dimensional ring array metasurface designed based on periodic structure element can form hollow focusing rings,which can meet the requirements of trapping I2 molecules,and realize optical storage.
NETL
NSTL
万方数据