wherein r is radius of the nano metal ball, ?? is the wavelength of the incident light, ???m is the dielectric coefficient of the air, ???p is the dielectric coefficient of the nano-metal ball, ??????p is the real part of the dielectric coefficient ???p of the nano metal ball, ??????p is an imaginary part of the dielectric coefficient ???p of the nano metal ball, ??=2??f, and f is a frequency of t