An FBG is manufactured in optical fiber through an inscription process using a laser. At Fibos, we produce FBGs using the phase mask approach with either a UV or femtosecond laser. The two different manufacturing methods produce different types of gratings and Fibos can help select the right grating for your specific application.
The beam from the laser (either UV or femtosecond) is shaped and focused through a cylindrical lens, then passes through a phase mask that has the desired Bragg grating period. As the light passes through this mask, only a portion of the laser irradiates the fiber and causes the periodic refractive index change. Several parameters can be tuned in this manufacturing process to vary the reflectivity of the FBG, spectral width and spectral shape. The time it takes to produce an FBG is typically <1 min., but alignment, fiber preparation and placement take ~10 mins. The femtosecond process allows for transjacket inscription and automation that will reduce the manufacturing time and improve grating quality. Fibos is actively advancing the manufacturing process.
Next: Learn more about the basics of fiber optics used in both telecommunications and sensing applications here.