Technology

The Fibre Bragg Grating (FBG) works on the principle that a UV laser shining on a coating-stripped fibre can induce refractive index modulation of the fibre core. These changes, through the use of phase or amplitude masks, can be designed and the masks fabricated to a required specification.

The way that light behaves when it comes to these sections of fibre is dictated by the spacing between each refractive index interface and the effective refractive index of the fibre core. Light of a particular wavelength is reflected from these interfaces and it is possible to measure this wavelength.

When there is a change in the environment that the fibre is in there will be a resulting shift of this wavelength, for example when a strain is imparted onto the fibre. Through calibration this shift can be related back to the parameter that is under investigation, such as strain, temperature etc.