What is the ideal wavelength for propagation in optic fibres?

  • Context: Undergrad 
  • Thread starter Thread starter Neural
  • Start date Start date
  • Tags Tags
    Optic Propagation
Click For Summary

Discussion Overview

The discussion revolves around the concept of the ideal wavelength for propagation in optical fibers, exploring reasons for its existence and implications for signal integrity. Participants consider various factors such as light absorption, transparency, dispersion, and mode propagation in the context of fiber optics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the need for a single ideal wavelength, suggesting that wavelength division multiplexing could be more beneficial.
  • Another participant proposes that the ideal wavelength is associated with minimum light absorption losses, indicating that there is a specific wavelength where these losses are minimized for the material used.
  • A different viewpoint suggests that minimal dispersion is the primary reason for selecting an ideal wavelength, with specific mention of 1300 nm for minimal loss and 1500 nm for minimal dispersion.
  • There is a discussion about the nature of dispersion in relation to monochromatic light, with one participant seeking clarification on how dispersion affects short pulses of light in optical fibers.
  • One participant elaborates on the concept of pulse integrity, explaining that short pulses consist of multiple wavelengths and that minimizing dispersion is crucial for maintaining signal quality.

Areas of Agreement / Disagreement

Participants express differing views on the factors contributing to the ideal wavelength for optical fiber propagation, with no consensus reached on a single definitive reason. Some agree on the importance of absorption and dispersion, while others challenge the necessity of a single wavelength.

Contextual Notes

Participants discuss various aspects of light behavior in optical fibers, including absorption, dispersion, and the implications for signal integrity, but the discussion does not resolve the complexities involved in these phenomena.

Neural
Messages
3
Reaction score
0
I was asked this question

Why is there an ideal wavelength for propagation in optic fibres?

a. Light absorption losses are minimum
b. The fibre has its greatest transparency at the ideal wavelength
c. Rayleigh scattering is greatest at this wavelength
d. Total internal reflection occurs only at this wavelength
e. The number of modes is at a minimum only at this wavelength

with these possible answers anyone know what ones they are I can't find out.

thanx
 
Science news on Phys.org
I really don't know why anyone would want one wavelength at all. Wavelength division multiplexing rocks.
 
maybe I should have worded it differently

Why is there an ideal wavelength for propagation in optic fibres?

how about "Out of these possible answers which ones give the ideal wavelength for propagation in optic fibres?"
 
I would guess "a", since light absorption is based on wavelength. So there would be a wavelength at which absorption losses are minimum for the given material.
 
its ok I found them its a and b thanks anyways:wink:
 
Actually, the biggest reason is minimal dispersion. Most fibers have their minimal loss at 1300 nm. Operation is usually at 1500 nm though because the dispersion is minimum there. This means very short pulses will lose their integrity more slowly.

Njorl
 
Originally posted by Njorl
Actually, the biggest reason is minimal dispersion. Most fibers have their minimal loss at 1300 nm. Operation is usually at 1500 nm though because the dispersion is minimum there. This means very short pulses will lose their integrity more slowly.

Njorl

I'm not getting something here. Could you tell me what is dispersing if the light is monochromatic? OR do you mean that for wavelengths near 1500 nm (say 1490 to 1510 nm) there is little dispersion?
 
The signals are made of short pulses. The shorter you can make a pulse, the more info you can send. But when you start getting to very short pulses, the true nature of the lightwave starts to cause problems.

A monochromatic lightwave must be infinitely long. This may surprise you. If it is finite, it is actually the superposition of many waves. If it is many wavelengths long, then almost all the signal is in a frequency that looks like a simple monochromatic source. If it is a short pulse, a significant amount of energy will be in a noticeably different wavelengths (though still pretty close to the fundamental frequency). If you want to keep the integrity of the pulsetrain, all of these different wavelengths should travel at the same speed. In other words, dispersion should be minimized.

Njorl
 
This is intriguing. I'm going to look at this closer. Thanks.
 

Similar threads

Undergrad Why can't we use opaque object in optical fibres?
  • · Replies 8 ·
Replies
8
Views
2K
Graduate Modes of Propagation in an Optical Fibre
  • · Replies 3 ·
Replies
3
Views
7K
Undergrad How does Total Internal Reflection in a mm/sm fiber work?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Energy Redistribution in Lorentz Oscillator Model with Pure Radiation Damping
  • · Replies 2 ·
Replies
2
Views
2K
What does it mean that when light is reflected the "wavelengths of each contributing hue are subtracted"?
  • · Replies 16 ·
Replies
16
Views
2K
How does graded-index material reduce pulse spreading in optical fibres?
  • · Replies 5 ·
Replies
5
Views
2K
Graduate How Does Nonlinear Optics Impact Light Propagation in Media?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Gradient Force of an optical near field
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Condenser lens retrofit for a lighting application
  • · Replies 24 ·
Replies
24
Views
4K
Graduate Birefringence in in uniaxial optical media and Snell's law
  • · Replies 6 ·
Replies
6
Views
4K