Multipole optimization of light focusing by silicon nanosphere structures

We investigate the applicability of coupled multipole model and its modification in framework zero-order Born approximation for modeling light focusing by finite-size nanostructures silicon nanospheres, supporting electric magnetic dipole quadrupole resonances. The results based on analytical approximations are verified comparison with numerical simulations performed T-matrix method. Using evolutionary algorithm optimization, we apply developed approach to design nanosphere metalenses predefined properties. obtained demonstrate a strong optimization potential suggested calculation scheme engineering ultrathin metalenses.