Induced Bragg Gratings in Optical Fibers and Waveguides Using an Ultrafast Infrared Laser and a Phase Mask

Figure 12

(a) Increase in Δ𝑛 as a function of exposure time for gratings written through the polymer coating with 250𝜇J pulses and a 𝑓=19 mm cylindrical lens (black squares) and gratings written on stripped SMF-28 fibre (gray triangles); (b) Long-term continued grating growth on stripped SMF-28 fiber.

(a)

(b)