Tm3+ cladding-doped fiber for selective wavelength filtering in high-power pump lasers

Scattering and reflection of transmission band power in a fiber amplifier cause increased bit-error rates through multiple path interference (MPI). We report a passive method for reducing MPI contributions from the front facet of a 980-nm fiber-Bragg-grating-stabilized pump laser by use of a Tm3+-doped fiber pigtail between the diode facet and the fiber Bragg grating. Optical return loss in the C band is reduced to below -30 dB.