Please provide the fundamental physical formula and explain the physical significance of each parameter involved.
The fundamental physical formula for the Bragg wavelength (λB) in a Fiber Bragg Grating (FBG) is:
λB = 2neffΛ
Here’s the physical significance of each parameter:
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λB: Bragg Wavelength
This is the central wavelength of light that is reflected by the FBG. When broadband light travels through the fiber, the FBG selectively reflects a narrow band of wavelengths centered at the Bragg wavelength, while transmitting the rest. This reflected wavelength is sensitive to changes in temperature and strain, making FBGs excellent sensors. -
neff: Effective Refractive Index
This represents the effective refractive index of the fiber core at the Bragg wavelength. It is an average refractive index experienced by the guided light in the core. The effective refractive index is influenced by the material composition of the fiber, the wavelength of light, and the physical state (temperature, strain) of the fiber. -
Λ: Grating Period
This is the physical distance between consecutive Bragg grating periods (the periodic variations in the refractive index along the fiber core). It is essentially the “spacing” of the grating.
Changes in temperature and strain directly affect both the effective refractive index (neff) and the grating period (Λ), leading to a shift in the Bragg wavelength (λB). This property is fundamental to the operation of OFSCN® Fiber Bragg Grating sensors.
For a foundational understanding of Fiber Bragg Gratings, you can refer to our bare FBG products:
- OFSCN® Polyacrylate Fiber Bragg Gratings / Fiber Bragg Grating Strings (bare)
- OFSCN® Polyimide Fiber Bragg Gratings / Fiber Bragg Grating Strings (bare)
- OFSCN® High-Strength Fiber Bragg Gratings / Fiber Bragg Grating Strings (Bare)
Here is a standard image illustrating FBG technology:
