Embleme Atom&NanoOpticsGroup

News


Research Areas


Experimental facilities


Publications


Team

Contacts

News


Optical Tamm state on a femtosecond time scale


Femto_timescale
A new paper has been published in Physical Review A. In this work, we investigated the temporal dynamics of the optical Tamm state (OTS) that arises at the interface between a one-dimensional photonic crystal and a gold nanofilm. The temporal dynamics was measured by two methods: (1) the spectral method, which is based on the analysis of the spectral composition of reflected light, and (2) the probe method, i.e., by embedding an inertialess probe into the OTS mode. It was found that the temporal dynamics of OTS formation is determined by the quality factor of the photonic-crystal/nanofilm microcavity with a characteristic time of OTS formation in the range of 100 to 300 fs.
Tamm state

Optical Tamm state and extraordinary light transmission through a nanoaperture

Microcavity Vs Metal film
Fig.1

Optical diode
Fig.2
A new paper has been published in Physical Review A. The effect of an extraordinary transmission (ET) of light through an array of nanoapertures has been observed for the first time by Ebbesen et al. The effect describes the light transmission through a nanoaperture array, which is considerably higher than predicted by the Bethe-Bouwkamp theory. The ET effect is due to the excitation of propagating plasmons.
We have shown another way to enhance transmission through a nanoaperture: due to the appearance of an optical Tamm state field at the interface of the planar structure “metamaterial–metal-film with hole”, Fig.1 (a). The 28-fold enhanced transmission of light through a single nanohole in Au film has been experimentally demonstrated. Moreover we have shown theoretically that this enhancement can be as large as 800% to the light flux incident on the aperture with an optimal cross section, Fig.2.

Subwavelength light localization based on optical nonlinearity and light polarization

SHR A new paper has been published in Optics Letters. An SHR can be also considered as a nanolocalized radiation source. From this viewpoint, the SHR has a number of merits in compare with other nanostructures. First, there is no accompanying background of the excitation radiation (which is very high with nanoparticles). Second, the transmission of the radiation through the is significantly higher than through the nanohole of the same size. Third, since the SHR is created in a metal film, it is capable of withstanding a higher intensity of the radiation incident on it than isolated nanoparticles, and, correspondingly, as a nonlinear element, can be more efficient.

Giant optical nonlinearity of a single plasmonic nanostructure

SHR
A new paper has been published in Optics Express. We realize giant optical nonlinearity of a single plasmonic nanostructure - a Split Hole Resonator (SHR). We demonstrate the use of SHR as highly effective nonlinear optical element for: (1) generation of third harmonic from a single SHR and (2) efficient multiphoton luminescence from a single SHR.SHR nanostructure formed in aluminum film. On the Figure below: (a) an electron microscope image of the nanostructure formed by a nanohole of 380 nm diameter and nanorod of 220 nm (length) × 120 nm (width), (b) calculated enhancement of the electric field amplitude upon irradiation of the nanostructure of Figure (a) by a plane monochromatic wave with a wavelength of 1560 nm, (c) an optical image of the nanostructure upon its laser irradiation at a wavelength of 1560 nm and detection at the THG wavelength, and (d) measured spectrum of radiation that forms optical image presented on Figure (c). The incident radiation is polarized along the direction of the nanorod of the nanostructure.

Proposed a new element for nanooptics and nanoplasmonics: Split Hole Resonator (SHR)

SHR We propose and experimentally realize a new element for nanoplasmonics which we call a Split Hole Resonator (SHR). The SHR is the marriage of two basic elements of nanoplasmonics, a nanohole and a nanorod (see the Figure below). 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. 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; (iii) the construction of a polarization-ultrasensitive nanoelement; and finally, as a practical application, (iv) the building up of an all-optical display.

Atom-femto trap

Theory

Femto trap

A new paper has been published in Physical Review A. A single atom “at rest” is an ideal physical object for many fundamental and applied investigations. A good approximation is an atom that is cooled by laser light and localized in a trap. However, a potential localizing the atom provides an perturbing effect on both external and internal degrees of freedom of the atom. The best situation is the cooling of the atom to a temperature corresponding to the energy of the atomic ground state, where the atom occupies the minimum phase space. Although the spatial motion of the atom is minimal in the ground state, this motion affects the internal degrees of freedom. Most fundamental and applied investigations are focused on the internal degrees of freedom.
We propose and investigate approach to the minimization of the effect of the localizing field on the atom – Atom Femto Trap. Its essence is the use of the short-term and time-periodic action of the laser field on the spatial motion of a very slow atom. In such a scheme, the atom is free of the perturbing effect of the localizing field for a time interval (1 – tp / T ), where tp is the duration of the action and T is its repetition period. When femto second pulses are used, the relative time interval during which the atom is situated in the localizing field may be very short, i.e., 10 -7 -10 -6 , i.e., the atom is almost at rest. The atomic dynamics in a three-dimensional pulsed optical dipole trap is considered in detail. It covers all key features of the atomic dynamics in the trap, including the dipole-dipole interaction between trapped atoms due to the exchange of virtual photons between the atoms and the chaotic behavior. Analytical solutions are obtained for the relaxation and laser Liouvillians, which describe the dissipation and laser excitation in the system, respectively.

www.isan.troitsk.ru

Institute for spectroscopy RAS, Fizicheskaya Str., 5, Troitsk, Moscow, 142190 Russia

phone: +7 495 851-02-33

e-mail: atom.nano.optics@gmail.com