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What is FBG?
(Fiber Bragg Grating)
A Fiber Bragg Grating (FBG) is a periodic modification of the refractive index inside the core of an optical fiber that selectively reflects a specific wavelength of light while allowing other wavelengths to pass through. This optical structure acts as a wavelength-selective reflector and is widely used for controlling, filtering, and sensing optical signals.
Its primary purpose is to provide precise wavelength management and high-sensitivity measurement capabilities in fiber-based photonic systems. By encoding a controlled refractive index pattern directly into the fiber, FBGs enable compact, passive, and highly stable optical components that can operate in demanding environments. They are extensively used in fiber optic sensing, fiber lasers, telecommunications, aerospace systems, and industrial monitoring, where accurate measurement of parameters such as temperature, strain, pressure, or vibration is required.
HOW a Fiber Bragg Grating Works
A Fiber Bragg Grating operates by using the interaction between guided light and a periodic structure embedded in an optical fiber. The process can be divided into three main steps.
Periodic Index Modulation
A precise pattern of alternating refractive index variations is created within the fiber core using techniques such as ultraviolet inscription. This periodic structure forms a grating that interacts with specific wavelengths of transmitted light.
Selective Light Reflection
When broadband or multi-wavelength light travels through the fiber, the grating reflects a narrow wavelength band known as the Bragg wavelength. The reflected wavelength depends on the grating period and the optical properties of the fiber, while the remaining wavelengths continue propagating through the fiber.
Sensing and Signal Processing
External changes such as temperature, mechanical strain, or pressure modify the grating period and refractive index of the fiber, causing a measurable shift in the reflected wavelength. By monitoring this shift, FBG-based systems can perform highly accurate distributed measurements in environments where traditional electronic sensors may be unsuitable.
What are the APPLICATIONS of FBG?
