Transmission through thin gold film

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SUMMARY

The discussion focuses on estimating the transmission of light through a 20nm thick gold film at 77K, using a wavelength of 1μm. Key parameters include a DC conductivity of σDC = 2 x 108 Ω-1 m-1 and a carrier density of n = 5.9 x 1028 m-3. The dielectric function is calculated using the formula ε(ω) = 1 - (ωp22) + (iσDC0ω), which leads to confusion regarding the absorption contribution and the reflection coefficient, R.

PREREQUISITES
  • Understanding of dielectric functions in materials
  • Familiarity with plasmon frequency calculations
  • Knowledge of light transmission and reflection coefficients
  • Basic principles of conductivity and carrier density in metals
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  • Study the calculation of dielectric functions in metals
  • Learn about the relationship between absorption and the imaginary part of the index of refraction
  • Research methods to compute reflection coefficients for thin films
  • Explore the impact of temperature on the optical properties of metals
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Physicists, materials scientists, and optical engineers interested in the behavior of light in thin metallic films, particularly in applications involving plasmonics and photonics.

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Homework Statement



Estimate the transmission of light with \lambda=1\mu m that is transmitted through 20nm thick gold film at 77k where

The DC conductivity:

\sigma_{DC}=2*10^8 \Omega^{-1} m^{-1})

The carrier density:

n=5.9*10^28 m^{-3})

and the plasmon frequency:

\frac{\omega_p}{2\pi}=2.18*10^{15} HzUse n to estimate absorption.

Homework Equations



\epsilon(\omega)=1-\frac{\omega_p^2}{\omega^2} + \frac{i\sigma_{DC}}{\epsilon_0\omega}

The Attempt at a Solution



OK. So, I know I should do this problem by computing the dielectric function at the given frequency and then finding the reflection coefficient from that. However, when I do this, I get the imaginary part being much much bigger than the real part.

This mean the imaginary part of N, the index of refraction, is equal to the real part of N, and thus, R becoms equal to one. I know this isn't the case.

The second problem:

I confused on how to account for the absorption in the dielectric function. Any hints would be greatly appreciated. Thanks!

(I hope this is enough info. I'm pressed for time, so if you need any more info, please ask, and I'll try my best to provide.)
 

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