“Digitally” addressable and localized on a nanometer-sized scale laser light spot

Abstract

We propose and experimentally realize sub-wavelength light localization based on optical nonlinearity of a single nonlinear -element in nanoplasmonics -a split hole resonator (SHR). Here, we demonstrate the use of the SHR as a highly efficient nonlinear optical element for: (1) the generation of the third harmonic from a single SHR; (2) the excitation of intense multiphoton luminescence from a single SHR; (3) the realization of a polarization-ultrasensitive nanoelement; and finally, as a practical application, (4) the building up of an all-optical display. I. SHR NANOSTRUCTURE AND ITS MERITSIn this paper, we propose and experimentally realize a novel element for nanoplasmonics that combines a nanoparticle and a nanohole into a new nanoobject. As a particular example of such a new element, we build up a split-hole resonator (SHR) that is composed of a nanorod and a nanohole, as is shown in Fig. 1. One of the main merits of the marriage of the two basic elements of nanoplasmonics, the nanoparticle and the nanohole, is to realize true monopole nanoantenna for light having wavelength of the surface plasmon resonance over a large wavelength range, namely, from the UV to the IR range. At resonance, the peak field intensity in SHR occurs at the single tip of the nanorod inside the nanohole. The peak field in the SHR is much stronger than the peak fields of the nanorod and nanohole, since the field in the SHR is enhanced by the following two mechanisms: the surface plasmon resonance excitation and the lightning-rod effect. Fig. 1. The main idea of the formation of a SHR and its operation, spatial distributions of the near field calculated by the FDTD method for aluminum nanostructures exposed to irradiation at a wavelength of 1560 nm: (a) a nanorod 50 × 180 nm, (b) a nanohole with a diameter of 400 nm in an aluminum film 50 nm thick, (c) an SHR nanostructure formed by the nanohole (b) and the nanorod (c).The use of SHRs in nonlinear nanoplasmonics is of special interest for the following reasons [1,2]: (i) the nanohole ensures the absence of a background from the excitation radiation, which is strongly weakened by a low transmission of the nanohole; (ii) the metal screen in which SHR is made ensures an efficient heat removal by the metal film, which, in turn, ensures the stability of the nanostructure to high-intensity radiation, making it possible to realize highly efficient nonlinear optical transformations [2]; (iii) at high intensities of the excitation field, an increase in the temperature of nanostructures does not cause a decrease in the Q factor of the plasmon resonance (resistive heating losses), because the metal film of the SHR efficiently removes heat [2]; (iv) the polarizability of a nanorod is higher than for a nanohole [3], therefore, the use of nanorods ensures a high optical nonlinearity of SHR nanostructures. II. NONLINEAR OPTICAL PROPERTIES OF A SINGLE SHR NANOSTRUCTUREAs a material for the creation of an SHR, we used aluminum. Investigations of SHRs were performed using radiation at a wavelength of 15...