Scattering from lossy medium whose refractive index is unity

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Discussion Overview

The discussion revolves around the scattering of light from a thin transparent plate with a refractive index equal to that of air, which also exhibits a small loss. Participants explore the mechanisms of light scattering in this context, particularly when the light enters at an acute angle.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant proposes that there may be a mechanism for scattering light towards the upper right from the plate, despite the refractive index being the same as air.
  • Another participant states that for an absorptive material, the refractive index becomes complex, but asserts that this does not lead to scattering out of the defined plane of incidence.
  • A participant seeks clarification on whether the loss component in the complex refractive index could result in a bending of light similar to refraction, indicating a potential for counterintuitive scattering.
  • A later reply confirms that the loss component can indeed lead to a bending effect, but does not elaborate on the implications for scattering.

Areas of Agreement / Disagreement

Participants express differing views on the possibility of scattering light in the described scenario. While some acknowledge the complexity of the refractive index and its implications, there is no consensus on whether scattering towards the upper right is feasible.

Contextual Notes

The discussion includes assumptions about the behavior of light in a medium with a complex refractive index and the implications of loss on scattering, which remain unresolved.

Swamp Thing
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Consider a thin transparent plate surrounded by air. The plate's refractive index is exactly the same as the air's, but it does have a small loss (say of the order of 1%).

Let the plate be vertical and normal to our "page" or your computer screen. A laser beam passes through the plate at an acute angle such as 5 degrees, say from the lower right to the upper left.

Now is there any mechanism in this system by which some of the light would be scattered towards the upper right? (FWIW, I arrived at this conjecture while following some train of thought that probably wouldn't interest anyone here).

If there is such a process, where can I read more about it? Does it have a name? Would the scattered energy form a beam similar in width to the incident one?
 
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For an absorptive material, the index of refraction becomes a complex quantity. Nevertheless it won't lead to scattering out of the plane defined by the normal to the surface and the incidence vector.
 
Thank you!
In my post, the question is about scattering within (consistent with) the constraint that you specified, but in a direction that is still counter intuitive. The direction I am asking about is similar to total internal reflection but with refractive index being the same as air.

You note that absorption is included in a complex coefficient -- so if I understand correctly, the loss component can result in refraction-like bending?
 
Swamp Thing said:
You note that absorption is included in a complex coefficient -- so if I understand correctly, the loss component can result in refraction-like bending?
Yes
 
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