Fibre laser with an intracavity polariser based on a long-period fibre grating

An all-fibre Er-doped laser emitting linearly polarised radiation is built. The laser uses a long-period fibre grating as a polarisation-dependent absorbing filter. The use of such an intracavity filter provides the degree of polarisation of output radiation as high as 98 % for a differential lasing efficiency of 45 %.