(a) Spectra of reflected femtosecond laser pulses at different incidence angles (left), comparison of scattered SPP pulse spectrum (black line), incident pulse spectrum (dashed line), reflected pulse spectrum at optimal SPP coupling angle (green line), and difference spectrum (square markers) between incident and reflected pulse spectra (middle), spectral bandwidth (FWHM) of the SPP excitation by prism coupling for Au films (orange line) and Ag films (black line) (right).^[48] (b) Combined impact of group velocity and loss dispersion on SPP pulse transmission over one propagation length on Al/, Ag/, and Au/silica waveguides: Upper plots show total (GVD- plus LD-induced) percentage pulse broadening; lower plots show normalized output pulse intensity, as functions of input pulse duration and center wavelength.^[49]