Azimuthally symmetric long-period fibre grating fabrication with a TEM01*-mode CO2 laser

We present a fabrication method that produces azimuthally symmetric long-period fibre gratings using a carbon dioxide laser operating in the TEM01*-mode. The outlay and optimization of the optical system are introduced, and the long-period fibre grating fabrication method is outlined. A uniform long-period grating written in a boron-doped fibre exhibited a maximum transmission loss of 10.83 dB at 1538.5 nm. The peak transmission loss of a non-uniform long-period grating also written in the boron-doped fibre yielded a value of 10.25 dB at 1552.6 nm. The polarization properties of the fabricated long-period fibre gratings were investigated to determine the quality of the grating structures. The uniform long-period grating structure exhibited a maximum polarization-dependent loss of 0.97 dB at 1542.1 nm, and the non-uniform long-period grating yielded a maximum polarization-dependent loss of 2.48 dB at 1551.4 nm.