Number of modes in optical fiber

In summary, the conversation discusses the possibility of a single mode fiber becoming multimode if the wavelength of light passed through it is small enough. The equation for determining the number of modes in a fiber is also mentioned, with a potential outcome of 2 modes for a fiber with an operational wavelength of 1300nm and a wavelength of 633nm being used. The individual also mentions an issue with their image not showing a uniform mode or pattern, suggesting the possibility of having a multimode fiber.
  • #1
says
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Homework Statement


Can a single mode fiber become multimode if the wavelength of the light passed through it is small enough?

I put a HeNe laser (633nm) through what I thought was a single mode fiber. If it's supposed to operate at 1300nm, then would a low wavelength of 633nm cause multiple modes in the single mode fiber?

Homework Equations


number of modes = operational wavelength / wavelength used

The Attempt at a Solution


number of modes = 1300nm/633nm = (approx.) 2 modes?

I'm not sure why my image isn't showing a uniform mode / pattern.
 

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  • #2
says said:

Homework Statement


Can a single mode fiber become multimode if the wavelength of the light passed through it is small enough?

I put a HeNe laser (633nm) through what I thought was a single mode fiber. If it's supposed to operate at 1300nm, then would a low wavelength of 633nm cause multiple modes in the single mode fiber?

Homework Equations


number of modes = operational wavelength / wavelength used

The Attempt at a Solution


number of modes = 1300nm/633nm = (approx.) 2 modes?

I'm not sure why my image isn't showing a uniform mode / pattern.
Maybe you have a multimode fibre?
 

Related to Number of modes in optical fiber

1. What is the significance of the number of modes in optical fiber?

The number of modes in optical fiber determines how much data can be transmitted through the fiber. It is an important factor in determining the bandwidth and speed of the fiber optic communication system.

2. How is the number of modes in optical fiber determined?

The number of modes in optical fiber is determined by the diameter of the fiber core and the refractive index of the core and cladding. The higher the diameter of the core and the lower the refractive index, the more modes the fiber can support.

3. What is the difference between single-mode and multi-mode fiber in terms of number of modes?

Single-mode fiber has a smaller core diameter and can only support one mode of light, while multi-mode fiber has a larger core diameter and can support multiple modes of light. Therefore, single-mode fiber has a lower number of modes compared to multi-mode fiber.

4. How does the number of modes affect the quality of the optical signal?

A higher number of modes in optical fiber can lead to increased signal distortion and attenuation, resulting in a poorer quality signal. This is why single-mode fiber, with its lower number of modes, is often preferred for long-distance and high-speed communication.

5. Can the number of modes in optical fiber be changed?

No, the number of modes in optical fiber is determined by the physical properties of the fiber and cannot be changed. However, different types of fiber can be used to achieve a desired number of modes, such as single-mode or multi-mode fiber.

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