When light fall on a metal, it will have certain phenomena. It will absorb, reflect, penetrate or transmit through metal, which will depend on the permeability, permittivity, penetration depth and band gap energy of metal.
If the light having sufficient energy then the light will excite the metal ions and it will generate free electron so metal will reflect it and it will absorb by the atom so atom will have negative permittivity for a that particular wavelength.
If the light does not having sufficient energy to excite the atoms of the metal then it will be transparent for that wavelength and permittivity will also be positive in that case. So metals have a positive imaginary and negative real part of permittivity, which is varying according to the frequency applied to it for a desired frequency we can design a particular circuit so that it will generate SPR. By using a spherical structure we can use it for trapping of light isnce light is moving in the direction of the tangent of geometry. Tangent of the spare also makes an spare so the light could be trap inside it.
In the arrangement (a), light excites plasmons via a grating coupler. If the grating constant is b, then light wave vector is increased by an additional term2Π/b, and the SP´s dispersion relation can be matched by a component of light vector parallel to the surface. For an angle of incidence equaling Θo the resonance condition takes the form:
If the light does not having sufficient energy to excite the atoms of the metal then it will be transparent for that wavelength and permittivity will also be positive in that case. So metals have a positive imaginary and negative real part of permittivity, which is varying according to the frequency applied to it for a desired frequency we can design a particular circuit so that it will generate SPR. By using a spherical structure we can use it for trapping of light isnce light is moving in the direction of the tangent of geometry. Tangent of the spare also makes an spare so the light could be trap inside it.
In the arrangement (a), light excites plasmons via a grating coupler. If the grating constant is b, then light wave vector is increased by an additional term2Π/b, and the SP´s dispersion relation can be matched by a component of light vector parallel to the surface. For an angle of incidence equaling Θo the resonance condition takes the form:
Here are some relative links:-
Light - Metal Interaction
Light - Metal Interaction
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