How to understand the refractive index of metals

[zhanghe]

for an example, polycrystalline silver, its index is n=0.135 and k =3.999 at the wavelength of 633nm, what does the nk mean, is that telling us the wavelength in the silver equals 633/0.135 nm ? and how to calculate the refractive angle in the metal?
Give a good explanation, please.

 

[Dr Transport]

Silver is a metal, which has a skin depth, after which the incident radiation does not penetrate any further. Look in the later chapters of Born & Wolf, Principles of Optics in the chapter about optics of metals. The refractive index is a complex quantity in metals because of absorption.

 

[charng]

The refractive index of a material is a measure of how much the speed of light is reduced when passing through that material. In the case of metals, the refractive index is often described using two values, n and k.

The value of n represents the real part of the refractive index and is related to the speed of light in the material. In the example given, the value of n=0.135 for polycrystalline silver at a wavelength of 633nm means that the speed of light is reduced to 0.135 times its speed in a vacuum when passing through this material.

The value of k represents the imaginary part of the refractive index and is related to the absorption of light in the material. In the example given, the value of k=3.999 means that the material has a very high absorption of light at a wavelength of 633nm.

The combination of n and k can be used to calculate the complex refractive index, which is important for understanding the behavior of light in the material. This can be done using the formula n + ik, where i is the imaginary unit (√-1).

The nk value does not represent the wavelength in the silver. It is simply a way of representing the complex refractive index using two values.

To calculate the refractive angle in the metal, you would need to know the angle of incidence, n and k values, and the wavelength of light. Using these values, you can apply Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the refractive indices of the two materials. This will allow you to calculate the angle of refraction in the metal.

In summary, the nk values for a material, such as polycrystalline silver, represent the real and imaginary parts of the complex refractive index and can be used to calculate the behavior of light in that material. To calculate the refractive angle in the metal, you would need to use Snell's Law and the given values.