1030 nm amplified spontaneous emission suppression in Yb-doped fiber amplifier operating near 976 nm

A newly-designed Yb-doped fiber type, intended to enhance 976 nm lasing by suppressing the spectral component including 1030 nm amplified spontaneous emission (ASE), was thoroughly researched. To implement an extremely sharp short-bandpass spectral filter, several suitably selected high-index absorber rods were incorporated into the fiber cladding. Thus, the concept of such a filter allows for a relatively accurate stop-band position adjustment as a result of the highly fiber-bend-dependent state of the intermodes resonance core-rod interaction. Finally, the impact of enhancing the power conversion efficiency (PCE) of the fiber amplifier emitting at a wavelength of 976 nm, by shifting the stop-band, is justified and demonstrated in this study.