We investigate the high order anapole mode in single dielectric nanostructure with high refractive index fromeigenmode perspective. We find that the anapole mode in both cylinder and sphere can only occur in thefollowing two situations:(1) If only one mode is involved, the combined phase of intrinsic and extrinsic phaseshould be equal to 2π at certain frequency that is close to the resonance. (2) If two leaky modes are involved,the combined phase for each mode must be 2π at same frequency which is located between two resonances.
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