Artur A. Kuzin

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.

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.

Split hole resonator: A nanoscale UV light source

Due to a strong light absorption by metals, it is believed that plasmonic nanostructures cannot be used for generating intensive radiation harmonics in the UV spectral range. We present results of investigation of the nonlinear optical interaction of laser radiation with a single gold nanostructure in the geometry of the Split-Hole Resonator (SHR) [1, 2] under the-state-of-the-art experimental realized conditions: (1) the laser pulse duration is ultimately short (two cycles of the laser pulse wave) to maximally reduce the thermal effects on the nanostructure; (2) the laser light intensity is ultimately high and close to the air ionization threshold; (3) the geometry of the nanostructure is optimal ensuring a record-high efficiency of the nonlinear optical interaction; and (4) the SHR nanostructure is formed in a single crystal gold nanofilm that is flat on the atomic level. Several multipole plasmon resonances can simultaneously be excited in the SHR nanostructure. A strong nonlinear optical interaction at the frequencies of these resonances that leads to (i) the second-harmonic generation, (ii) the third harmonic generation (THG), and (iii) the light generation at mixed frequencies. The THG near field amplitude reaches 0.6% of the fundamental frequency field amplitude, which enables the creation of UV radiation sources with a record high intensity. The UV light may find many important applications including biomedical ones (such as cancer therapy).

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.

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.

Nanophotonics and nanoplasmonics elements produced by atom optics methods

We review current status and perspectives of nanolithography via atom optics and its application in production of nanophotonics and nanoplasmonics elements: gold optical nano antennas, plasmonic wave guides, nanostructures formed by organic molecules.