Long-wavelength spectral filtering in anisotropic tapered fiber

We report on special tapered large mode area (LMA) polarization-maintaining fibers demonstrating inherit long-wavelength spectral filtering. The attenuation more than 25 dB of long-wavelength spectral range arising after amplified spontaneous emission (ASE) of a preamplifier, and also preservation of polarization state (extinction ratio more than 20 dB) and mode composition is presented in these fibers. Integration of this approach into the amplifier gain medium is promising for solving the problem of effective spectral filtration and polarized light generation.