V. O. Bessonov

Observation of hybrid state of Tamm and surface plasmon-polaritons in one-dimensional photonic crystals

Experimental observation of hybrid mode of Tamm plasmon-polariton and surface plasmon-polariton is reported. The hybrid state is excited in one-dimensional photonic crystal terminated by semitransparent metal film under conditions of total internal reflection for transverse-magnetic-polarized light. Coupling between Tamm and surface plasmon-polaritons leads to repulsion of their dispersion curves controlled by metal film thickness.

Direct observation of dynamic modes excited in a magnetic insulator by pure spin current

Excitation of magnetization dynamics by pure spin currents has been recently recognized as an enabling mechanism for spintronics and magnonics, which allows implementation of spin-torque devices based on low-damping insulating magnetic materials. Here we report the first spatially-resolved study of the dynamic modes excited by pure spin current in nanometer-thick microscopic insulating Yttrium Iron Garnet disks. We show that these modes exhibit nonlinear self-broadening preventing the formation of the self-localized magnetic bullet, which plays a crucial role in the stabilization of the single-mode magnetization oscillations in all-metallic systems. This peculiarity associated with the efficient nonlinear mode coupling in low-damping materials can be among the main factors governing the interaction of pure spin currents with the dynamic magnetization in high-quality magnetic insulators.

Femtosecond relaxation dynamics of surface plasmon-polaritons in the vicinity of fano-type resonance

Temporal modification of femtosecond laser pulses reflected from planar periodic metal nanostructures with resonant excitation of surface plasmon-polaritons is experimentally studied. Spectral time-resolved measurements of the second-order cross-correlation function performed with the pulse duration comparable with the surface plasmon-polariton relaxation time (about 100 fs) show the strong spectral dependence of the envelope of the reflected femtosecond pulse described by Fano-resonance parameters.

Second-harmonic generation enhancement in the presence of Tamm plasmon-polaritons

Resonant enhancement of second-harmonic generation (SHG) intensity from a thin metal film is demonstrated in a Tamm plasmon-polariton mode excited at a metal/photonic crystal interface using nonlinear spectroscopy. Nonlinear effects enhancement in proposed structures exhibit strong polarization dependence (1:200 for the orthogonal fundamental polarizations). SHG enhancement factor evinces considerable angular dependence, rising from 50 for the 45° angle of incidence to 170 for the 10° angle of incidence. The results are analyzed numerically using a nonlinear transfer matrix technique. The findings elucidate the potential of Tamm plasmon-polaritons in the nonlinear optical applications.

DC-induced generation of the reflected second harmonic in silicon

DC-induced generation of the reflected second harmonic is experimentally observed on the surface of a centrosymmetric silicon single crystal. A direct current with a surface density of jmax ∼ 103 A/cm2 violates the symmetry of the electron distribution function and induces the optical second harmonic with an intensity corresponding to the dipole quadratic susceptibility χ(2)d(jmax) ∼ 3 × 10−15 m/V.

Measurements of the femtosecond relaxation dynamics of Tamm plasmon-polaritons

This paper reports on measurements of the lifetime of Tamm plasmon-polaritons (TPPs) excited in a 1D photonic-crystal/thin-metal-film structure. A femtosecond pulse reflected from a structure of this kind is found to be significantly distorted if its spectrum overlaps with the Tamm plasmon resonance. It is shown that the TPP lifetime possesses strong polarization and angular dependence. It varies from 20 fs for p-polarized light to 40 fs for s-polarized light at a 45° angle of incidence. The reported lifetime of Tamm plasmons is several times smaller than the previously reported lifetime of surface plasmons.

Femtosecond Pulse Shaping with Plasmonic Crystals

The temporal shaping of femtosecond laser pulses reflected from a one-dimensional plasmonic crystal using a commercially available polymer grating coated with a silver film is experimentally demonstrated by timeresolved measurements of the intensity correlation function. Shaping is achieved by the excitation of surface plasmon-polaritons with a lifetime comparable to the 130 fs laser pulse duration. The variety of data obtained demonstrate the flexible shaping of fs-pulses by delaying, advancing, splitting, broadening, compressing, and changing the topological properties of the pulse with the plasmonic crystals under study.

Second harmonic generation induced by mechanical stresses in silicon

The optical second-harmonic generation induced by the external mechanical tension of the (001 ) silicon surface has been detected. A change in the spectrum of the second harmonic, which is caused by the modification of the band structure of silicon near the critical points E’o and E1 under mechanical tension, has been observed. The direct contribution to the optical second harmonic from changes in the band structure of silicon under tension is experimentally separated from the electric-field-induced co ntribution associated with the redistribution of the surface charge under the action of mechanical stresses.

Chiral charge pumping in graphene deposited on a magnetic insulator

We demonstrate experimentally that a sizable chiral charge pumping can be achieved at room temperature in graphene/yttrium iron garnet (YIG) bilayer systems. The effect, which cannot be attributed to the ordinary spin pumping, reveals itself in the creation of a dc electric field/voltage in graphene as a response to the dynamic magnetic excitations (spin waves) in an adjacent out-of-plane magnetized YIG film. We show that the induced voltage changes its sign when the orientation of the static magnetization is reversed, clearly indicating the broken mirror reflection symmetry about the planes normal to the graphene/YIG interface. The strength of effect shows a nonmonotonous dependence on the spin-wave frequency, in agreement with the proposed theoretical model.

Polymer X-ray refractive nano-lenses fabricated by additive technology

The present work demonstrates the potential applicability of additive manufacturing to X-Ray refractive nano-lenses. A compound refractive lens with a radius of 5 µm was produced by the two-photon polymerization induced lithography. It was successfully tested at the X-ray microfocus laboratory source and a focal spot of 5 μm was measured. An amorphous nature of polymer material combined with the potential of additive technologies may result in a significantly enhanced focusing performance compared to the best examples of modern X-ray compound refractive lenses.