Optical Path length in core fiber of fiber optic faceplate

In summary, the conversation discusses the timing spread in the time of flight of photons through fibers in a fiber optic faceplate. The minimum and maximum time for photon propagation are determined by a photon traveling axially through the fiber and a photon entering the fiber at the maximum angle allowed, respectively. The path length for a ray not entering orthogonal to the surface normal is described by Hecht's equation, which does not account for the diameter of the fiber. However, the diameter of the fiber does not affect the path length as the ray will be reflected multiple times during its journey. Therefore, the path length can be found by using the fiber length and the angle.
  • #1
jcates7
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Homework Statement


Sorry if this is the wrong section. Please redirect me if there is a more appropriate one.

I'm looking at the timing spread in the time of flight of photons through fibers in a fiber optic faceplate. Essentially the minimum time for photons to propagate through one of the fibers would come from a photon traveling axially through the fiber and not interacting with the fiber walls. The maximum time would come from a photon entering the fiber at the maximum angle allowed within the aperture of the fiber. This photon would undergo total internal reflection along the length of the fiber - producing a longer path length and therefore a longer time to propagate. Hecht describes the path length for a ray not entering orthogonal to the surface normal of one of the fibers to be path length=finber length/cos(transmitted angle). This doesn't physically make sense to me, as it doesn't account for the diameter of the fiber. One can imagine that if the length of the fiber stayed constant and the diameter increased, the path length of rays will increase significantly. This equation doesn't account for this. Could anyone possible shed some light on this?

Thanks,

Josh


Homework Equations





The Attempt at a Solution

 
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  • #2
The diameter of the fiber doesn't matter. You know the ray will be reflected multiple times as it travels. So picture the path as a series of zig-zags through the fiber. To find the length of the actual diagonal path, all you need to know is the fiber length and the angle. (And a little trig, of course.)
 

1. What is the purpose of the optical path length in a core fiber of a fiber optic faceplate?

The optical path length in a core fiber of a fiber optic faceplate is used to transmit light signals from one end of the fiber to the other. It helps to maintain the integrity of the signal and reduce losses, allowing for efficient transmission of information.

2. How does the optical path length affect the performance of a fiber optic faceplate?

The length of the optical path in a core fiber can impact the performance of a fiber optic faceplate in several ways. A longer path length can result in increased signal attenuation, while a shorter path length may cause signal distortion. Therefore, it is important to carefully control the path length to optimize the performance of the faceplate.

3. What factors can affect the optical path length in a core fiber?

The optical path length can be affected by factors such as the refractive index of the fiber material, the diameter of the core, and the angle of incidence of the light. These factors can impact the speed and direction of light as it travels through the fiber, ultimately affecting the path length.

4. How is the optical path length measured in a fiber optic faceplate?

The optical path length in a fiber optic faceplate can be measured using devices such as an interferometer or an optical time domain reflectometer (OTDR). These instruments use light pulses to determine the length of the fiber and can provide accurate measurements of the path length.

5. Can the optical path length be adjusted in a fiber optic faceplate?

Yes, the optical path length can be adjusted in a fiber optic faceplate by changing the refractive index of the fiber material, adjusting the diameter of the core, or altering the angle of incidence of the light. These adjustments can help to optimize the performance of the faceplate for specific applications.

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