Proximion is the leading supplier of advanced Fiber Bragg Gratings (FBGs) based products with a capability to manufacture straight, chirped or tilted FBGs with a customized group delay profile. Proximion uses a unique and flexible writing technique, which allows for smaller series but also enables scaling to high volume production due to a highly automated production process.
Fiber Bragg Gratings
Our Fiber Bragg Gratings
What Is a Fiber Bragg Grating and How Does It Work?
A Fiber Bragg Grating (FBG) is a wavelength-selective reflector written directly into the core of an optical fiber. It is formed from a precise, repeating pattern of minute changes in the fiber’s refractive index. When light travels through the fiber, reflections from this pattern reinforce one another at a particular wavelength, known as the Bragg wavelength. That wavelength is reflected, while most other wavelengths continue through the fiber. This principle makes Fiber Bragg Gratings highly versatile components for filtering, sensing, signal control and dispersion management.
How FBG Technology Responds to Light and Physical Change
The wavelength reflected by an FBG is governed mainly by the spacing of the grating and the effective refractive index of the fiber. If either changes, the reflected wavelength shifts. This is the basis of FBG sensors. Strain stretches or compresses the grating, while temperature changes both the fiber’s dimensions and refractive index. With appropriate sensor design and packaging, the same response can be used to measure pressure, vibration, displacement and other physical parameters. An optical interrogator tracks the wavelength shift and converts it into accurate measurement data.
FBG technology can also be designed to control the timing and spectral shape of optical signals. A uniform FBG has a constant grating period. In Chirped Fiber Bragg Gratings, the period varies along the fiber, causing different wavelengths to be reflected at different positions. The resulting wavelength-dependent delay can be engineered for dispersion compensation, dispersion emulation, pulse stretching or compression, spectral analysis and other advanced photonic functions.
How Are Fiber Bragg Gratings Made?
Manufacturing a high-performance Fiber Bragg Grating requires exceptional optical and mechanical precision. A specially prepared fiber is exposed to an ultraviolet interference pattern, creating permanent refractive-index changes within a core only a few micrometres across. The position, spacing and strength of those changes must be tightly controlled because very small variations can affect wavelength, bandwidth, reflectivity and group delay.
Proximion’s proprietary production platform combines a two-beam interferometer with highly accurate motion control. Successive interference patterns can be written with sub-nanometre precision over grating lengths exceeding ten metres. By changing the pattern continuously under software control, Proximion can manufacture straight, tilted and ultra-long chirped designs and tailor their optical behaviour. This enables Custom Fiber Bragg Gratings with application-specific wavelength ranges, spectral responses and dispersion characteristics. The automated process supports specialist prototypes as well as scalable production.
What Benefits Does FBG Technology Offer?
Fiber Bragg Gratings are compact, lightweight and passive. They can perform low-loss optical processing within the fiber itself and integrate readily with other fiber-optic components. For sensing, FBGs are immune to electromagnetic interference, require no electrical power at the measurement point and can operate in locations where conventional electronic sensors are unsuitable. Multiple FBG sensors can also be multiplexed along one fiber, reducing cabling and allowing many sensing points to be monitored over long distances.
Typical Applications for Fiber Bragg Gratings
In telecommunications and quantum communications, Chirped Fiber Bragg Gratings are used for chromatic dispersion management, network testing and the precise control of photon wave packets. Other photonic applications include optical filtering and monitoring, microwave signal processing, ultrafast pulse shaping, spectroscopy and optical coherence tomography.
FBG sensors are widely used for temperature and strain measurement, structural health monitoring, industrial process control, cryogenic systems, energy infrastructure and aerospace applications. Whether the requirement is a single optical element, a sensor array or a complete module, Custom Fiber Bragg Gratings provide a flexible platform for controlling light and turning physical change into reliable optical data.
The Chirped FBG – a key component for telecoms and optical measurement
A chirped FBG is a special type of FBG in which the period of the grating varies linearly along its length. The result is a wavelength selective filter where a broad range of wavelengths are reflected from different locations along the CFBG.
In this way, the CFBG can be designed to modify the characteristics of a spectrum, such as narrowing or broadening the optical pulse. Click the link below to see the multiple applications of this remarkable optical element.
