How can light propagate through Hollow optical fiber.

Click For Summary

Discussion Overview

The discussion revolves around the propagation of light through hollow optical fibers, specifically focusing on the mechanisms that allow this to occur despite the absence of total internal reflection. Participants explore concepts such as photonic bandgap fibers and their operational principles, as well as the implications for transmission efficiency and applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that traditional optical fibers rely on total internal reflection, while hollow optical fibers utilize different principles, potentially involving photonic bandgap effects.
  • There is a question about whether light propagates through the air or the glass in hollow fibers, with some indicating it propagates in the air.
  • One participant suggests that hollow fibers may reduce path loss compared to glass fibers, raising questions about the efficiency of reflections in these structures.
  • Clarifications are made regarding the distinction between photonic bandgap fibers and hollow light pipes, emphasizing that the former should be analyzed using wave optics rather than ray optics.
  • Another participant provides a reference to a theoretical analysis of air-guiding photonic bandgap fibers, highlighting their unique properties and operational principles.
  • There is a suggestion that the reactive walls of photonic fibers may reflect energy effectively, drawing an analogy to metal waveguides.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the exact mechanisms of light propagation in hollow optical fibers, with multiple competing views on the role of photonic bandgap effects and the nature of the propagation medium. The discussion remains unresolved with no consensus reached.

Contextual Notes

Participants mention various assumptions and definitions related to the types of fibers being discussed, including the distinction between photonic bandgap fibers and hollow optical fibers. The complexity of the topic suggests that further exploration of the underlying physics is necessary.

Who May Find This Useful

This discussion may be of interest to those studying optical fibers, photonics, or related fields, particularly individuals looking to understand the principles behind hollow optical fibers and their applications.

KT KIM
Messages
24
Reaction score
0
Now I am studying a bit of optical fibers. And of course generally optical fiber works because of total reflection property of the light, which happens when the light from higher medium hits the lower medium material.

However I recently found out that there also is a thing 'Hollow optical fiber' which the core is hollowed out, filled with an air. I think the propagation should not happen because total reflection won't work here, but it works perfectly fine. I've hit some papers and got some keywords like 'band gap waveguide', 'photonic crystal' etc... but still can not understand it.

Can you give me a brief explanation, or just let me know where should I start with first?
 
Science news on Phys.org
@KT KIM: How about a few references about this idea? If you've been reading then save us from having to search for what you're describing.

The hollow fibre seems to avoid the path loss through the glass so, if reflections can be made to rival the efficiency of TIR, the net loss over a long path could be less. We tend to assume that TIR is the only reflection worth considering. The above link seems to stress the improved transmission speed so, perhaps it's not so much aimed at long distance paths but at local connections. 3.5dB per km is not going to take you across the Atlantic easily.
 
KT KIM said:
Can you give me a brief explanation, or just let me know where should I start with first?

It's not clear to me if you are talking about photonic bandgap fibers (which can have a cavity in the center) or some sort of hollow 'light pipe'.

Photonic bandgap fibers are best analyzed in terms of wave optics, not ray optics. The interior is very inhomogeneous and is designed to allow only certain field modes to propagate. Having air (or vacuum) in the center is useful for high-power applications because there's no damage to the material.
 
  • Like
Likes   Reactions: sophiecentaur
Andy Resnick said:
It's not clear to me if you are talking about photonic bandgap fibers (which can have a cavity in the center) or some sort of hollow 'light pipe'.

Photonic bandgap fibers are best analyzed in terms of wave optics, not ray optics. The interior is very inhomogeneous and is designed to allow only certain field modes to propagate. Having air (or vacuum) in the center is useful for high-power applications because there's no damage to the material.

More exact to say, I wanted to talked about, Photonic crystal fiber (including photonic bandgap fiber), maybe 'hollow optical fiber' was not a good word choice, excuse me.
 
KT KIM said:
More exact to say, I wanted to talked about, Photonic crystal fiber (including photonic bandgap fiber), maybe 'hollow optical fiber' was not a good word choice, excuse me.

Try starting with this:

OPTICS LETTERS / Vol. 25, No. 2 / January 15, 2000
Analysis of air-guiding photonic bandgap fibers
Jes Broeng, Stig E. Barkou, Thomas Søndergaard, and Anders Bjarklev

We present what is to our knowledge the first theoretical analysis of air-guiding photonic bandgap fibers. The
fibers are characterized by a large hollow core and a microstructured cladding exhibiting photonic bandgap
effects. Using an efficient, full-vectorial numerical method, we explain the operational principle of the fibers
and obtain detailed information about the properties of the air-guided modes. This information includes
accurate determination of the modes’ spectral extent, cutoff properties, and mode-field distributions.
 
I presume the photonic action gives us a hollow tube with reactive walls, which therefore reflect nearly all the energy. It seems equivalent to a metal waveguide with deep corrugations.
 

Similar threads

Undergrad Light coupling in fiber optic cables
  • · Replies 22 ·
Replies
22
Views
4K
Undergrad Help Needed for Lens Selection for Fiber optics
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Connect: Coupling Light from 2 LEDs into a Single Fiber
  • · Replies 2 ·
Replies
2
Views
3K
Graduate How can the electric field of optical fibers be visualized?
  • · Replies 1 ·
Replies
1
Views
1K
Graduate How can I determine the length of a Multimode fiber?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Rearranging the equation for the cutoff condition in optical fibers
  • · Replies 2 ·
Replies
2
Views
1K
Dark fiber optic cables as Earthquake detectors
  • · Replies 9 ·
Replies
9
Views
2K
Undergrad How Much Light Can Fiber Optic Cables Carry?
  • · Replies 4 ·
Replies
4
Views
3K
Graduate Closely-Spaced Modes in Birefringent Single-Mode Fibers?
  • · Replies 5 ·
Replies
5
Views
2K
High School A good introduction on light propagation mode
  • · Replies 1 ·
Replies
1
Views
1K