Point-by-Point Compression of CO2 Infrared Laser for Fabrication of Waist-Enlarged Long Period Fiber Bragg Gratings

We propose a method using CO2 laser irradiation to heat and squeeze a standard SMF-28 fiber, forming long-period fiber gratings (LPFGs). By controlling the motor’s squeezing speed and time, we can increase the cladding diameter of optical fibers from 125 μm to a maximum of 160 μm. This expanded structure allows the formation of LPFGs with a minimum period length of 0.325 mm. This method produces LPFGs with larger waist diameters and shorter periods than traditional tapering methods, exhibiting more spectral transmission peaks with a maximum bandwidth less than 3 nm.