FLUORESCENCE AND SUPERFLUORESCENCE LINE NARROWING AND TUNABILITY OF ND-3+ DOPED FIBERS

The inhomogeneous behavior of the 1.06mum-Neodymium transitions in dop ed optical fibers have been investigated, using the fluorescence line narrowing technique, pumping on the F-4(3/4) and F-4(5/2) sublevels at 4 K. Each observed transition has been identified. As the pump wavele ngth varies, the shift of the main fluorescence line is 40 nm, with th e two pumping levels. We have studied the spectral behavior of the sup erfluorescence as a function of the pump wavelength, the temperature, and the absorbed power. The spectral evolution depends on lambda(p) wi th a 19 nm-tuning range at low temperature. At 300 K, the quasihomogen eous behavior of the transition decreases the tunability to 14 nm. Bas ed on these results, we present a simple technique permitting precise prediction of gain and spectral line shapes of superfluorescent Nd-dop ed fiber sources.