A. S. Baturin

Giant optical nonlinearity of a single plasmonic nanostructure

We realize giant optical nonlinearity of a single plasmonic nanostructure which we call a split hole resonator (SHR). The SHR is the marriage of two basic elements of nanoplasmonics, a nanohole and a nanorod. A peak field intensity in the SHR occurs at the single tip of the nanorod inside the nanohole. The peak field is much stronger than those of the nanorod and nanohole, because the SHR field involves contributions from the following two field-enhancement mechanisms: (1) the excitation of surface plasmon resonances and (2) the lightning-rod effect. Here, we demonstrate the use of the SHR as a highly efficient nonlinear optical element for: (i) the generation of the third harmonic from a single SHR; (ii) the excitation of intense multiphoton luminescence from a single SHR.

Nanolithography based on an atom pinhole camera

In modern experimental physics the pinhole camera is used when the creation of a focusing element (lens) is difficult. We have experimentally realized a method of image construction in atom optics, based on the idea of an optical pinhole camera. With the use of an atom pinhole camera we have built an array of identical arbitrary-shaped atomic nanostructures with the minimum size of an individual nanostructure element down to 30 nm on an Si surface. The possibility of 30 nm lithography by means of atoms, molecules and clusters has been shown.

Single nanohole and photonic crystal: wavelength selective enhanced transmission of light

For the first time we have demonstrated an approach to control transmission of light through a single nanohole with the use of photon crystal microcavity. By use of the approach 28-fold enhanced transmission of light through a single nanohole in Au film has been experimentally demonstrated. The approach has the following advantages: (1) it enables to considerably increase transmission of light through a single nanohole, (2) the increase in transmission is unaffected by the hole diameter, (3) the transmission of nanohole is selective in frequency, the width of the resonance ~λ/90, (4) no auxiliary structures are necessary on the surface of the Au film (extra nanoholes, grooves, etc.).

Single nanohole and photoluminescence: nanolocalized and wavelength tunable light source

We are first to demonstrate a broadband, nanometer-scale, and background-free light source that is based on photoluminescence of a single nanohole in an Au film. We show that a nanohole with a diameter of as small as 20 nm in a 200-nm thick Au film can be used for this purpose. Further development of the localized source that involves the use of a photon-crystal microcavity with a Q-factor of 100 makes it possible to create a 30-fold enhanced, narrowband tunable light source and with a narrow directivity of the radiation.

Extremely high transmission of light through a nanohole inside a photonic crystal

The transmission of light through single nanoholes with diameters considerably smaller than the wavelength of light (smaller than λ/10) is experimentally studied. The nanoholes were made in a gold film, which is a part of a photonic crystal forming a microcavity with the quality factor Q ≈ 100. A 28-fold increase in the transmission of light through a nanohole inside the microcavity compared to transmission through a nanohole in a gold film is demonstrated. The high spectral selectivity of light transmission through a nanohole is discovered, which is characterized by two features: (i) the transmission maximum is located at the resonance wavelength of the microcavity and (ii) the peak full width at half-maximum is about λ/90.

Calculation of the thicknesses and elastic properties of thin-film coatings using atomic-force acoustic microscopy data

The feasibility of applying atomic-force acoustic microscopy to measure the elastic properties of thin-film coatings and their thickness in the range from several to several hundreds of nanometers is studied. In practice, this technique can be used to study diamond-like coatings. The key point of our method is application of “flat” tips, which provide a constant tip-surface contact area and, hence, a constant contact stiffness. The reason for using such tips is that experimental data for thin-film structures gained with standard (rounded) tips cannot be given an adequate quantitative interpretation. Numerical simulation is used to evaluate the thickness and indentation modulus of a coating from contact stiffness kcont measured by atomic-force acoustic microscopy.

Doping of graphite by an alkaline-earth metal to reduce the work function

A technique for reducing the work function of a field-emission graphite cathode by doping it by an alkaline-earth metal (barium) is suggested. A model of formation of a barium monolayer on the cathode surface is proposed. Field-emission tests show that the operating voltage of the doped cathode is lower than that of the undoped one with the same emission current.

Prediction of field emitter cathode lifetime based on measurement of I–V curves☆

Abstract A technique is presented, which allows the prediction of field emitter cathode lifetime without long-term direct measurements of cathode parameters stability. This technique is based on periodic measurements of cathode I – V characteristics. Moreover, it allows performing a post-experiment optimization for the appropriate choice of the feedback system to provide a stable operation during a long time. The proposed technique was applied to study the emission properties of reticulated vitreous carbon (RVC) and thermo-enlarged graphite (TEG). For the given cathodes, the characteristic time of the cathode destruction was estimated.

A nanohole in a thin metal film as an efficient nonlinear optical element

The nonlinear optical properties of single nanoholes and nanoslits fabricated in gold and aluminum nanofilms are studied by third harmonic generation (THG). It is shown that the extremely high third-order optical susceptibility of aluminum and the presence of strong plasmon resonance of a single nanohole in an aluminum film make possible an efficient nanolocalized radiation source at the third harmonic frequency. The THG efficiency for a single nanohole in a thin metal film can be close to unity for an exciting laser radiation intensity on the order of 1013 W/cm2.

Simulation of contact stiffness of a hemispherical island inclusion

Numerical analysis is carried out for constructing a model simulating the contact stiffness of a solitary hemispherical island inclusion in an infinitely extended substrate. The contact stiffness is measured using atomic force acoustic microscopy with tips having a constant contact radius. Finite element analysis using the isotropic model of the materials is employed for this purpose. The model can be used for studying nanocomposite materials.