Observation of NBOHC Excitation in Pulsed Yb-Doped Fiber Amplifiers

We present observations of interactions involving nonbridging oxygen hole center (NBOHC) defects in a pulsed Yb-doped fiber amplifier. When operated at high peak power, the amplifier produces a visible red luminescence, possibly attributable to the NBOHC defect, with five distinct, apparently gain-narrowed, emission bands. Interestingly, both the absorption and continuous-wave-excited emission spectra seem to decompose into five Gaussian bands that are consistent with the locations of the bands observed in the pulse-excited spectrum.