Hi Umer,
As Aabid sir discussed about FBG sensors.
I want to share some information about FBG sensors, which is One of the most commonly used and broadly deployed optical sensors,
which reflects a wavelength of light that shifts in response to variations in temperature and/or strain.
FBGs are constructed by using holographic interference or a phase mask to expose a short length of
photosensitive fiber to a periodic distribution of light intensity. The refractive index of the fiber
is permanently altered according to the intensity of light it is exposed to. The resulting periodic
variation in the refractive index is called a fiber Bragg grating.
When a broad-spectrum light beam is sent to an FBG, reflections from each segment of
alternating refractive index interfere constructively only for a specific wavelength of light,
called the Bragg wavelength. It has various advantages like FBG strain gages are
available with a variety of form factors and mounting options including epoxy, weldable, bolt-on, and embedded.