What is an FBG?

The Fiber Bragg Grating (FBG) is the sensing element packaged within an optical gauge sensor, or transducer. It's the foundation of Fibos technology and informs how we conduct optical measurements, as well as integrate with a signal conditioner.

From Wikipedia:

"Dr. Kenneth O. Hill is a physicist who specializes in the field of photonics. In the late 1970s, he discovered the phenomena of photosensitivity in optical fiber and has worked extensively in its applications.[1][2] He first demonstrated Fiber Bragg gratings and their applications in optical communication and optical sensor systems.[3] Further areas of his discovery and innovation include the phase mask technique for grating fabrication, fiber grating dispersion compensators, and wavelength selective fiber filters, multiplexers and demultiplexers.[4] This field of research has led to the ability to create high speed fiber optic networks as well as many other communication applications that have revolutionized the telecommunications industry."

The FBG was a Canadian invention and has been supported by Canadian researchers since the original discovery. This foundational technology was a key component for the telecommunications industry to grow and become a global leader, and it is this motivation that has kept the Canadian government interested in funding the development of the technology. The Canadian government still holds patents that protect FBG production in certain applications.

The FBG is written into the core of an optical fiber and forms a permanent change in the refractive index in a periodic manner within that area. The change in refractive index is achieved through controlled physical changes in the glass, referred to as a "grating", done with a laser. The grating acts like a tiny mirror inside the fiber and reflects a narrow slice of the spectrum, while allowing all other wavelengths to pass through. Fun fact: metamaterials use the same principle of reflecting specific wavelengths for different optical effects, such as forms of optical cloaking and invisibility.

Next: Learn how an FBG can be used as a sensing element for strain and temperature measurements here.