We fabricate a buried channel waveguide in neodymium-doped phosphate glass using a double line approach by femtosecond laser writing.Raman spectra reveal an expansion of the glass network in the laser irradiated region.Given the stress-induced positive refractive index change,waveguiding between two separated tracks is demonstrated.The refractive index difference profile of the waveguide is reconstructed from the measured near-field mode.Propagation loss is measured by scattering technique.Microluminescence spectra reveal that the Nd3+fluorescence property is not significantly affected by waveguide formation process,which indicates that the inscribed waveguide is a good candidate for active device.
Taking advantage of the dispersive Fourier transformation technique, the decaying evolution processes of doublepulse mode-locking in a single-walled carbon-nanotube-based Er-doped fiber laser are observed in detail for the first time to our knowledge. The decaying dynamics of the double-pulse mode-locking state is analyzed in the spectral and temporal domains. We reveal that the two pulses in one cluster disappear either simultaneously or one by one during the decaying processes of double-pulse mode-locking states. In addition, the spectral evolution patterns of the special double-pulse states(i.e., bound states) are extremely distinct at different decline rates of the pump power.
GUOMEI WANGGUANGWEI CHENWENLEI LICHAO ZENGHUIRAN YANG
