Interaction of laser radiation with metallic nanostructures accompanied with resonant excitation of surface plasmons-polaritons (SPP) is the subject of great interest for the applications of guiding light energy. In case of ultrashort laser pulses such interaction may result in strong reshaping of incident laser pulse which can provide us with information about SPP dynamics on metal-dielectric interface. At the same time, dynamics of SPP can be modified with periodic structuring of metal – by forming one-dimensional array of nanoslits or two-dimensional array of nanoholes, i.e. by forming planar plasmonic crystal structure. This structuring strongly modifies dispersion law of SPP and in the region of plasmonic band-gap one can expect to find out new features in SPP dynamics. However comprehensive temporal studies of plasmonic crystals have not been presented yet. In this paper femtosecond dynamics of resonantly excited SPP is studied in the vicinity of band-gap of planar plasmonic crystal. Measurements were performed using angular-resolved cross-correlation spectroscopy technique based on tunable Ti: Sapphire laser setup. One-dimensional plasmonic crystals were made by deposition of silver film on a substrate with 750 nm-period groove pattern. Figure 1 a) shows reflection spectra of plasmonic crystal with polarization of light perpendicular to the grooves (p-polarization) at different angles of incidence. At each angle two maxima of double Fano-type resonance refer to the resonant SPP excitation. Minimum between two branches of SPP at normal angle of incidence at wavelength about 750 nm represents plasmonic band-gap. At s-polarization of light reflectance spectra do not have resonant features. Cross-correlation function (CCF) of the reflected from the sample femtosecond pulse has symmetric Gauss-like shape at both plasmon-sensitive p-polarization and plasmon-insensitive s-polarization of light. Figure 1 b) shows spectrum of temporal difference between p- and s-polarization CCFs at 2° incidence (solid circles) exhibiting high temporal dynamics in the region of the SPP resonance at wavelengths about 725-750 nm. Moreover, in the center of the resonance CCF become broader and strongly asymmetric and its temporal position can not be unequivocally defined, dynamics of CCF in this region symbolically represented by open circles. Such spectral behavior of CCF demonstrates presence of strong SPP resonance.figureFigure 1. a) Reflectance spectra of plasmonic crystal. b) Time-difference spectrum of crosscorrelation function of femtosecond pulse reflected from plasmonic crystal at 2°.