The spectral properties of the transverse magneto-optical Kerr effect (TMOKE) in periodic metal-dielectric hybrid structures are studied, in particular with respect to the achievable magnitude. It is shown that the TMOKE is sensitive to the magneto-optical activity of the bismuth-substituted rare-earth iron garnet, which is used as a dielectric material in the investigated structures. For samples with larger Bi substitution level and, consequently, larger gyration 9
We demonstrate that the dispersion of surface plasmon polaritons in a periodically perforated gold film can be efficiently manipulated by femtosecond laser pulses with the wavelengths far from the intrinsic resonances of gold. Using a time-and frequency-resolved pump-probe technique we observe shifting of the plasmon polariton resonances with response times from 200 to 800 fs depending on the probe photon energy, through which we obtain comprehensive insight into the electron dynamics in gold. We show that Wood anomalies in the optical spectra provide pronounced resonances in differential transmission and reflection with magnitudes up to 3 % for moderate pump fluences of 0.5 mJ/cm 2 .PACS numbers: 73.20.Mf, 78.66.Bz, 78.67.Pt Nowadays plasmonics attracts much research interest in nanophotonics inspiring scientists to develop a new paradigm in data processing based on nanometallic circuitry 1,2 . The key object of plasmonics is a surface plasmon polariton (SPP) -a coupled oscillation of the electromagnetic field and the electron plasma in metals 3 . Excitation of a SPP leads to significant electromagnetic energy localization near the metal-dielectric interface, thereby enhancing nonlinear effects and light-matter interaction. Current state-of-the-art in telecommunications requires plasmonics to be active, i.e. a possibility for control by means of an external stimulus must be provided on the order of a few nanoseconds or shorter 4 .One of the approaches satisfying the strict criteria is magnetoplasmonics employing the influence of an external magnetic field on the SPP propagation constant 5,6 . While the modulation efficiency in magnetoplasmonic structures may be as large as tens of percent the operation rate is limited by the magnetization dynamics occurring on the nanoseconds timescale. Transient changes in the optical properties of plasmonic structures can be also achieved via application of intense femtosecond laser pulses 4,7-14 . Here, the real and imaginary parts of the dielectric constant of a metal change in the matter of several hundreds of femtoseconds 15-17 . Since the propagation constant of SPPs is determined by the permittivity of metal and dielectric this opens new horizons for ultrafast control of SPPs. However, the high reflectivity of smooth gold surfaces prevents most of the incident electromagnetic energy from absorption in the metal. Here, SPPs can be exploited to provide electromagnetic energy localization near the metal-dielectric interface and consequently to increase the energy absorption in gold 18,19 .Recently the optical response of plasmonic crystals with periodically perforated gold or perforated dielectric on top of gold was investigated using a two-color pumpprobe technique with the pump photon energy far from the SPP resonances 11,12 . It was demonstrated that the differential reflectivity of the probe beam tuned in resonance with a SPP can be modulated up to 10 % on a sub-picosecond timescale. Large values of the modulation parameter were accomplished by using intense laser pu...
The magneto-optical properties of a hybrid metal-dielectric structure consisting of a one-dimensional gold grating on top of a magnetic waveguide layer are studied experimentally and theoretically. It is demonstrated that a magnetic field applied in the longitudinal configuration (in the plane of the magnetic film and perpendicular to the slits in the gold grating) to the metal-dielectric structure modifies the field distribution of the optical modes and thus changes the mode excitation conditions. In the optical far field, this manifests in the alteration of the optical transmittance or reflectance when the structure becomes magnetized. This magneto-optical effect is shown to represent a novel class of effects related to the magnetic-field-induced modification of the Bloch modes of the periodic hybrid structure. That is why we define this effect as "longitudinal magnetophotonic intensity effect" (LMPIE). The LMPIE has two contributions, odd and even in magnetization. While the even LMPIE is maximal for the light polarized perpendicular to the grating slits (TM) and minimal for the orthogonal polarization (TE), the odd LMPIE takes maximum values at some intermediate polarization and vanishes for pure TM and TE polarizations. Two principal modes of the magnetic layer-TM and TE-acquire in the longitudinal magnetic field additional field components and thus turn into quasi-TM and quasi-TE modes, respectively. The largest LMPIE is observed for excitation of the antisymmetrical quasi-TE mode by TM-polarized light. The value of the LMPIE measured for the plasmonic structure with a magnetic film of Bi 2 Dy 1 Fe 4 Ga 1 O 12 composition is about 1% for the even effect and 2% for the odd one. However, the plasmonic structure with a magnetic film with a higher concentration of bismuth (Bi 2.97 Er 0.03 Fe 4 Al 0.5 Ga 0.5 O 12) gives significantly larger LMPIE: even LMPIE reaches 24% and odd LMPIE is 9%. Enhancement of the magneto-optical figure of merit (defined as the ratio of the specific Faraday angle of a magnetic film to its absorption coefficient) of the magnetic films potentially causes the even LMPIE to exceed 100% as is predicted by calculations. Thus, the nanostructured material described here may be considered as an ultrafast magnetophotonic light valve.
We obtain the temperature dependence of the homogeneous linewidth of excitons in GaAs quantum wells (QWs) and bulk GaAs using photoluminescence measurements. The results indicate that exciton scattering rates with optical phonons are larger in bulk GaAs than in QWs.
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