RESUMEN
Search for new types of efficient magnetoplasmonic structures that combine high transparency with strong magneto-optical (MO) activity is an actual problem. Here, we demonstrate that composite heterostructures based on thin perfectly-arranged opal films and a perforated cobalt nanolayer meet these requirements. Anomalous transmission appears due to periodic perforation of Co consistent with the regular set of voids between opal spheres, while resonantly enhanced MO response involves the effects of surface plasmon-polariton (SPP) excitation at opal/Co interface or those associated with photonic band gap (PBG) in opal photonic crrystals. We observed the enhancement of the MO effect of up to 0.6% in the spectral vicinity of the SPP excitation, and several times less strong effect close to the PBG, while the combined appearance of PBG and SPP decreases the resultant MO response. Observed resonant magneto-optical properties of opal/Co heterostructures show that they can be treated as functional self-assembled magnetoplasmonic crystals with resonantly enhanced and controllable MO effect.
RESUMEN
Hyperbolic metamaterials (HMM) based on multilayered metal/dielectric films or ordered arrays of metal nanorods in a dielectric matrix are extremely attractive optical materials for manipulating over the parameters of the light flow. One of the most promising tools for tuning the optical properties of metamaterialsin situis the application of an external magnetic field. However, for the case of HMM based on the ordered arrays of magneto-plasmonic nanostructures, this effect has not been clearly demonstrated until now. In this paper, we present the results of synthesis of HMM based on the highly-ordered arrays of bisegmented Au/Ni nanorods in porous anodic alumina templates and a detailed study of their optical and magneto-optical properties. Distinct enhancement of the magneto-optical (MO) effects along with their sign reversal is observed in the spectral vicinity of epsilon-near-zero and epsilon-near-pole spectral regions. The underlying mechanism is the amplification of the MO polarization plane rotation initiated by Ni segments followed by the light propagation in a strongly birefringent HMM. This stays in agreement with the phenomenological description and relevant numerical calculations.
RESUMEN
Porous films of anodic aluminum oxide are widely used as templates for the electrochemical preparation of functional nanocomposites containing ordered arrays of anisotropic nanostructures. In these structures, the volume fraction of the inclusion phase, which strongly determines the functional properties of the nanocomposite, is equal to the porosity of the initial template. For the range of systems, the most pronounced effects and the best functional properties are expected when the volume fraction of metal is less than 10%, whereas the porosity of anodic aluminum oxide typically exceeds this value. In the present work, the possibility of the application of anodic aluminum oxide for obtaining hyperbolic metamaterials in the form of nanocomposites with the metal volume fraction smaller than the template porosity is demonstrated for the first time. A decrease in the fraction of the pores accessible for electrodeposition is achieved by controlled blocking of the portion of pores during anodization when the template is formed. The effectiveness of the proposed approach has been shown in the example of obtaining nanocomposites containing Au nanorods arrays. The possibility for the control over the position of the resonance absorption band corresponding to the excitation of collective longitudinal oscillations of the electron gas in the nanorods in a wide range of wavelengths by controlled decreasing of the metal volume fraction, is shown.
RESUMEN
An ultrathin nonlinear optical (NLO) organic surface composed of numerous self-assembled frustum-shaped whispering-gallery-mode resonators displays both two-photon luminescence and second-harmonic-generation signals. A super-second-order increase of the NLO intensity with respect to pump power confirms the microlasing action and practical usefulness of the NLO organic surfaces.
RESUMEN
Chiral spectroscopic study: The intensities of second harmonic generation chiral spectroscopy are obtained from the dispersion of the nonlinear optical susceptibility components, as a function of wavelength for helicenbisquinone thin films (see figure). A single formalism fits all the data simultaneously, and the findings constitute an important milestone towards the development of a new experimental technique.