ИСТИНА

Active nanoplasmonics is a versatile area, which provides bright optical effects and light control at subwavelength scale by various physical or chemical external actions. The excitation of the surface plasmon-polaritons (SPP) in nanoplasmonic materials can be sensitive to the temperature, chemical surrounding, and magnetic field. Thus, in the plasmonic crystals, the femtosecond laser pulses induce fast heating of electron gas and modulation of its dielectric permittivity. The plasmonic crystals made from magnetic metals, which are also called magnetoplasmonic crystals, show resonantly enhanced transversal magneto-optical Kerr effect (TMOKE) via the modulation of the phase-matching condition of SPP by a magnetic field. In this work, the ultrafast enhancement of TMOKE by excitation of SPP at subpicosecond time scale is studied by the pump-probe optical spectroscopy of nickel magnetoplasmonic crystals. Three nickel nanogratings with different amplitudes of spatial harmonics in spatial profile were used as samples. Different Q-factors of the Fano-shape resonances in spectral vicinity of Wood’s anomaly are observed in TMOKE spectra and femtosecond differential reflectivity spectra for different grating’s profile. The maximum value of TMOKE and femtosecond differential reflectivity were obtained for the sample with the amplitude of the first spatial harmonic of 90 nm.