Light Traveling in both Directions in a fiber optic cable

Click For Summary

Discussion Overview

The discussion revolves around the behavior of light traveling in both directions within a fiber optic cable, specifically addressing concerns about potential interference between a 532nm laser and returning light around 694nm. The scope includes conceptual understanding of optics and the principles governing light propagation.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why returning light would not interfere with the outgoing laser light in a fiber optic setup.
  • Another participant suggests that the spectrometer uses two separate cables, which may explain the lack of interference.
  • A different participant argues that light traveling in opposite directions can coexist without interference, using an analogy of two people seeing each other across a room.
  • Another point raised involves the principle of superposition, indicating that light from different sources can be analyzed separately, and interference occurs only in overlapping regions, without inhibiting the propagation of either light source.

Areas of Agreement / Disagreement

Participants express differing views on the potential for interference, with some suggesting it would occur while others argue it would not. The discussion remains unresolved regarding the specifics of light behavior in this context.

Contextual Notes

Participants rely on various assumptions about the setup of the fiber optic system and the nature of light propagation, which may not be fully detailed or agreed upon.

HyperSniper
Messages
39
Reaction score
2
We have a spectrometer in our lab that collects light through a fiber optic cable, however it also sends a 532nm laser down this fiber optic cable.

My background isn't in optics, and it would seem to me that the returning light (which is typically around 694 nm) would interfere with each other. Why would this not be the case?
 
Science news on Phys.org
Okay, so it probably actually would be the case, this spectrometer actually uses two separate cables that are just bound in the same tube so it was hard to tell that is what is going on.
 
Actually it wouldn't. Think about it. If I'm on the right end of a room looking at you and you're on the left end of the room looking at me we can see each other fine despite the fact that your light and mine travel through the same space in opposite directions.
 
It might also help to consider the "principle of superposition", which applies to light in any application other than nonlinear optics. This priinciple means that you can analyze each source of light separately, and just add up all the results at the end. In regions where the light from both sources overlaps, you can get "interference", but that doesn't mean the propagation of one is inhibiting the propagation of the other, because you can still just add up the net results of both anywhere they don't overlap (like in your eyes or my eyes).
 

Similar threads

  • · Replies 22 ·
Replies
22
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K