Understanding AC and Optical Conductivity: Conflicting Information Clarified

In summary, there is confusion regarding the meaning of optical conductivity and AC conductivity. Some papers use plots of transmission and reflectivity, while others use a Drude-like expression. Textbooks do not provide a clear answer. The Drude model, when solved for conductivity, can be considered as either optical or AC depending on the frequency range. Additionally, there is a debate on whether optical conductivity refers specifically to photo-conductivity or conductivity at high frequencies.
  • #1
DeathbyGreen
84
16
Maybe someone can help me out; I've been seeing conflicting information on the meaning behind optical conductivity vs AC conductivity. Some papers seem to post plots of transmission and reflectivity, and others a Drude-like [itex] \sigma(\omega)[/itex]. In many textbooks I can't seem to find a satisfactory answer.

If we start with a system under a field [itex] E(t) = Ee^{i\omega t}[/itex], solve the Drude model to get [itex] \sigma(\omega)[/itex], is this an expression for optical conductivity or AC? And what are the geometries of both?
 
Physics news on Phys.org
  • #2
DeathbyGreen said:
If we start with a system under a field [itex] E(t) = Ee^{i\omega t}[/itex], solve the Drude model to get [itex] \sigma(\omega)[/itex], is this an expression for optical conductivity or AC? And what are the geometries of both?
I think this depends on frequency (radio- vs. optical).
 
  • #3
By optical conductivity, do you mean photo-conductivity, which is a material becoming conducting when exposed to light, or do you just mean conductivity at very high frequencies?
 
  • #4
I mean conductivity induced by irradiation; I've seen this called both optical and AC conductivity. Maybe it's just called AC because the light has a frequency and an analogy can be drawn between that and actual AC electricity with connected leads?
 

1. What is AC/Optical conductivity?

AC/Optical conductivity is a measurement of how well a material conducts electricity in the presence of an alternating electric field. It describes the ability of a material to carry an electrical current when subjected to high frequency electromagnetic radiation, such as visible light.

2. How is AC/Optical conductivity different from DC conductivity?

The main difference between AC/Optical conductivity and DC conductivity is the frequency of the electric field used in the measurement. DC conductivity measures the ability of a material to carry an electric current in the presence of a constant electric field, while AC/Optical conductivity measures its response to a changing electric field at high frequencies.

3. What factors affect AC/Optical conductivity?

AC/Optical conductivity is affected by a number of factors, including the material's composition, crystal structure, and temperature. It is also influenced by the frequency and intensity of the applied electric field, as well as any impurities or defects present in the material.

4. How is AC/Optical conductivity measured?

AC/Optical conductivity is typically measured using a technique called spectroscopy, which involves shining a beam of light of a specific frequency onto a sample and measuring the reflected or transmitted light. The amount of light absorbed or scattered by the material is then used to calculate its conductivity.

5. What are the applications of AC/Optical conductivity?

AC/Optical conductivity has many practical applications, including in the development of new electronic and optoelectronic devices. It is also used to study the properties of different materials and to understand their behavior under high-frequency electromagnetic fields. Additionally, AC/Optical conductivity measurements can provide valuable insights into the fundamental physics of materials and their interactions with light.

Similar threads

Replies
1
Views
691
Replies
12
Views
8K
  • Advanced Physics Homework Help
Replies
1
Views
2K
Replies
8
Views
2K
  • Calculus and Beyond Homework Help
Replies
2
Views
1K
  • Special and General Relativity
Replies
8
Views
2K
  • Quantum Interpretations and Foundations
Replies
8
Views
432
  • Advanced Physics Homework Help
Replies
4
Views
5K
  • Beyond the Standard Models
Replies
2
Views
2K
  • General Engineering
Replies
27
Views
8K
Back
Top