Evanescent Waves and Energy Conservation

Employing the Fourier transform method, the inconsistency between the trsditional definition of the light intensity 48 (where is the amplitude) in the scalar field theory and the Helmholtz wave equation is proved. The inconsistency means that "the evanescent waves can make the energy conservation law broken". The consistency between the accurate formula of the light intensity in the transverse plane (where kL is the phase) and the Helmholtz wave equation is also proved. Based on these results, the characteristics that the evanescent waves can't make energy flow is pointed out.