Fig. 2

Meta-atom design strategy and characterizations of three typical meta-atoms. a Simulated normal-mode intensity \({\left|{A}_{{\text{n}}}\right|}^{2}\) of the MIM meta-atom against their bar lengths \({L}_{u}\) and \({L}_{v}\), with the dashed curve marking \({\text{Min}}({\left|{A}_{{\text{n}}}\right|}^{2})\) for each \({L}_{u}\). b Simulated structural phase \({\Phi}_{{\text{Str}}}\) of the MIM meta-atom as a function of the bar length \({L}_{u}\) with \({L}_{v}\) taking the values on the \({\text{Min}}({\left|{A}_{{\text{n}}}\right|}^{2})\) curve in a correspondingly. Inset in b illustrates the basic structure of an MIM meta-atom. Three stars labelled as “1, 2, 3” correspond to three stars in a. c, d, e Upper panels are SEM pictures of three meta-atoms labelled as “1, 2, 3” in a and b, respectively; Lower panels depict the \({\left|{A}_{{\text{n}}}\right|}^{2}\) spectra obtained by simulations (red line) and measurements (red circle) and the simulated spectra of \({\Phi}_{{\text{Str}}}\) (blue line) for three meta-atoms denoted “1, 2, 3” in a and b. Dashed lines in these figures indicate the positions of working wavelength (λ = 1064 nm)