FBG Wavelength Reflection in Double-Clad MMF for 910 nm Laser Diode

In summary, a FBG (Fiber Bragg Grating) is being used in a double-clad multimode optical fiber with a 20 µm core diameter, along with a 910 nm laser diode as the light source. The Bragg reflection wavelength of a FBG is determined by the effective refractive index of the different guided modes, and the FBG can reflect each of these modes. However, in this case, the FBG has been designed to have a high reflection (99%) at a specific wavelength (910 nm), which is the LP01 wavelength. There are also three other guided modes (LP11, LP02, and LP21) present. The person is looking for resources that can explain the behavior
  • #1
Gilbert
6
2
Hi everyone!

I use a FBG in a double-clad multimode optical fiber of 20 µm core diameter, and a laser diode working at 910 nm as ligth source.

As the Bragg reflection wavelength of a FBG depends on the effective refractive index of the different guided modes (λFBG=2.neff.Λ , where Λ is the period), is it right to say that the FBG will reflect each of these modes? Or is a FBG only used to carry out reflection of a fixed wavelength, independantly of the modes?

Because in my case, the FBG has been designed to have a maximized reflection (99%) at 910 nm, which is the LP01 wavelength. But there are 3 other guided modes : LP11, LP02 and LP21.

Thanks in advance.

Gilbert.
 
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  • #2
Edit : is there any book or website that could explain the behavior of FBG with multimode fiber ?
 

1. What is FBG wavelength reflection in double-clad MMF?

FBG (Fiber Bragg Grating) wavelength reflection is a phenomenon where a specific wavelength of light is reflected back from a specialized fiber optic component called a Bragg grating. In double-clad MMF (Multi-Mode Fiber), the fiber has two layers, or "cladding", which allows for efficient transmission of light. This design allows for precise control and manipulation of light wavelengths.

2. How does FBG wavelength reflection work in relation to a 910 nm laser diode?

In a 910 nm laser diode, the FBG acts as a filter, reflecting only the desired wavelength of light (in this case, 910 nm) back into the laser cavity. This creates a feedback loop that stabilizes the laser's output and improves its performance.

3. What are the benefits of using FBG wavelength reflection in double-clad MMF for 910 nm laser diodes?

FBG wavelength reflection in double-clad MMF offers several benefits, including improved stability and precision of the laser's output, reduced noise and interference, and higher efficiency of light transmission. It also allows for tunability and control of the laser's wavelength, making it useful in various applications such as telecommunications and medical devices.

4. Are there any limitations to using FBG wavelength reflection in double-clad MMF for 910 nm laser diodes?

While FBG wavelength reflection is a highly effective method for stabilizing and improving laser performance, it does have some limitations. For example, the FBG must be precisely tuned to the desired wavelength, which can be challenging and time-consuming. Additionally, the FBG may also introduce some signal loss, which can affect the overall efficiency of the laser.

5. How is FBG wavelength reflection in double-clad MMF for 910 nm laser diodes used in research and industry?

FBG wavelength reflection in double-clad MMF is widely used in research and industry for various applications, such as fiber optic sensors, telecommunications, and laser-based medical devices. Its ability to precisely control light wavelengths and improve laser performance makes it a valuable tool in these fields.

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