Multi-Edge-Written Long-Period Fibre Gratings with Low PDL by Using High-Frequency CO₂ Laser Pulses

A novel long-period fibre grating (LPFG) with low polarization-dependent loss (PDL) is fabricated by using a multi-edge exposure method with high frequency CO₂ laser pulses. The experimental results show that the PDL of a triple-edge-written LPFG with a peak amplitude of -16.5dB can be as low as 0.22dB. These novel LPFGs can find important applications in optical communication and sensing.