Erbium-doped polarization-maintaining active optical fiber and preparation method thereof

The invention relates to an erbium-doped polarization maintaining active optical fiber, the cross section structure of which sequentially comprises a fiber core (1), a cladding (2), an inner coating (4) and an outer coating (5) from inside to outside. The cladding (2) is internally provided with two stress regions (3), the two stress regions (3) are symmetrically arranged on the two sides of the fiber core (1), the modulus of the inner coating (4) is smaller than the modulus of the outer coating (5), the refractive index difference delta 1 of the fiber core (1) relative to the cladding (2) is0.005 to 0.01, and the refractive index difference delta 2 of the stress regions (3) relative to the cladding (2) is -0.0080 to -0.0120. The absorption of the optical fiber is higher than that of a panda type polarization maintaining optical fiber, so that the use length of the optical fiber in a laser is shorter, and the same light beam quality and polarization characteristic as those in a low-power environment are obtai