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Did you know how fiber Bragg gratings play a key role in sensing technology?
Fiber Bragg Grating (FBG) is a distributed Bragg reflector built into a short section of optical fiber that can reflect light of a specific wavelength and transmit other wavelengths. This technology has become an important part of modern sensing technology and is widely used in various fields, such as structural health monitoring, temperature measurement, and pressure monitoring.
Fiber Bragg gratings work by creating periodic variations in the refractive index in the core of an optical fiber, generating a wavelength-specific dielectric mirror.
To understand the historical background of fiber gratings, we can go back to 1978, when Ken Hill, a researcher at Texas Tech University, first demonstrated gratings in optical fiber. Initially, these gratings were made using visible light laser structures, but in 1989, Gerald Meltz and his team developed a more flexible lateral holographic writing technique that allowed the laser to be shone from the side of the fiber, allowing more complex grating structures to be made.
Working Principle of Fiber Bragg Grating
The basic principle of fiber Bragg grating is based on Fresnel reflection. When light propagates between media with different refractive indices, it will be reflected and refracted at the interface. The reflected wavelength is called the Bragg wavelength, which is related to the effective refractive index of the fiber core and the grating period.
The formula for the Bragg wavelength is λB = 2neΛ, where ne is the effective refractive index of the fiber core and Λ is the period of the grating.
This property gives FBGs significant advantages in sensing applications because they can accurately detect specific environmental changes, such as temperature variations or mechanical deformations, by measuring tiny changes in reflected wavelength.
Types of Fiber Bragg Gratings
Fiber Bragg gratings can be divided into several types, depending on the photosensitizing mechanism used in their fabrication. Standard gratings are the most common type and are generally available in both hydrogenated and non-hydrogenated optical fibers. Other types such as Type II or regenerative gratings have their own specific properties and common application scenarios.
Standard gratings are often referred to as standard gratings, which have high reflectivity and can operate stably in a variety of environments.
Through different manufacturing techniques, various fiber Bragg gratings with different characteristics can be constructed. For example, fiber Bragg gratings with "activation" features can provide excellent environmental response, which is of great practical value in sensing technology.
Application of Fiber Bragg Grating in Sensing Technology
Fiber Bragg gratings are widely used in engineering structure health monitoring, gas and liquid sensors, medical diagnostic equipment and other fields. In terms of structural monitoring, these fiber Bragg gratings can be used to monitor the stability of bridges, tunnels and buildings, and detect potential problems in a timely manner by measuring tiny deformations and stress changes.
With the development of technology, the application scope of fiber Bragg grating is constantly expanding and playing a key role in modern science and technology.
In medicine, Fiber Bragg gratings can be used to provide precise measurements of physiological parameters, helping doctors better understand and diagnose their patients. In addition, the use of these fiber Bragg gratings can also greatly promote the development of security monitoring systems to ensure the safe operation of various industrial and municipal facilities.
Not only that, with the advancement of optical technology, the demand for fiber Bragg gratings is also growing, which has prompted continuous innovation in related manufacturing technologies and materials. Therefore, we may be faced with a question: In the future technological development, how will fiber Bragg gratings continue to influence the progress and security of various industries?
