ISSN 1064-2269, Journal of Communications Technology and Electronics, 2011, Vol. 56, No. 12, pp. 1471–1479. © Pleiades Publishing, Inc., 2011. Original Russian Text © E.S. Andrianov, A.A. Pukhov, A.V. Dorofeenko, A.P. Vinogradov, A.A. Lisyansky, 2011, published in Radiotekhnika i Elektronika, 2011, Vol. 56, No. 12, pp. 1501–1510. 1471 INTRODUCTION The fundamental limitation on the operation rate of future computers is imposed by ratio of the size of the system to the velocity of light. The rapid progress in plasmonics can be used to solve the problem owing to the application of metamaterials and the creation of the devices with subwavelength sizes. Recent interest in the optics of metamaterials (substances with negative per- mittivity or permeability) [1] has been driven mainly by the Pendry’s work [2], in which a superlens with the res- olution exceeding the diffraction limit was proposed. The new electrodynamics of metamaterials stimulated the development of theoretical proposals on the possi- ble applications: clocking [3, 4], hyperlenses [5–7], energy concentrators [8], etc. In spite of the absence of the natural metamaterials, the progress in plasmonics and nanotechnology allowed the creation of artificial optical metamaterials [9]. The working principle is based on the plasmon resonance of metal nanoparticles. A significant disadvantage of such materials is related to inadmissibly high loss. Active (amplifying) impurities can be used in the artificial metamaterials for the loss compensation [7, 10–12]. An example of such impurities in metamaterials is the simplest object of quantum plasmonics—metal nanoparticle that is surrounded by inversely excited quantum systems (molecules or quantum dots). The interaction of the surface plasmons (SPs) that are excited in the nanoparticles with the electromagnetic field of the inversely excited quantum dots (QDs) allows the transformation of the system into a quan- tum generator of plasmons (nanolaser). Note that the dipole nanolaser [13], spaser [12–14], and the nanola- ser on the magnetic mode [11] can be classified as nanolasers. The spaser, which was experimentally implemented in [15], is the most promising device. The spaser schematically represents a system of inversely excited two-level QDs that surround the plasmon nanoparticles. The working principle of the spaser is similar to the working principle of laser. SPs that are localized on the nanoparticle play the role of photons [14, 16–18], and the nanoparticle plays the role of cavity. In other words, the generation and amplification of the near fields of nanoparticles take place in the spaser. The amplification of the SPs is due to the nonradiative energy transfer from the QD. The process is based on the dipole–dipole or any alterna- tive near-field interaction [19] of the QD and plasmon nanoparticle. The process is effective owing to the fact that the probability of the nonradiative excitation of plasmon is greater than the probability of the radiative emission of photon by a factor of , where r is the distance between the centers of QD and nanoparticle and [20]. The generation of a relatively large number of plasmons leads to the stimulated emission of the QD to the plasmon mode and the development of the plasmon generation. Thus, the excitation of the plasmon mode by pump is performed via the QD exci- tation. The spaser operation can be controlled using rela- tively weak external fields. In the presence of the exter- nal field, the spaser can start working at the field fre- quency but the oscillation amplitude of the dipole moment will be determined by the pump level rather than the external field. The characteristic time and dynamics of the spaser transition from the intrinsic fre- quency to the field frequency are practically important. We may assume that the spaser can be used as an ampli- fier or switch. It may seem that the independence of the oscillation amplitude on the external fields impedes the applica- tion with amplification [21]. However, the results from [18] show that the spaser can work as an amplifier in the transient regime. In particular, in the transient regime, the spaser exhibits complicated nonlinear dynamics and the amplitude of the spaser oscillations can be sig- nificantly higher than the amplitudes of the initial and steady-state spaser oscillations. ( ) 3 kr - 2 k = πλ RADIO PHENOMENA IN SOLIDS AND PLASMA Dynamics of the Transient Regime of Spaser E. S. Andrianov, A. A. Pukhov, A. V. Dorofeenko, A. P. Vinogradov, and A. A. Lisyansky Received July 19, 2011 Abstract—The dynamics of the nonradiative excitation of plasmons in the surface plasmon amplifier by stimulated emission of radiation (spaser) that represents a two-level quantum dot in the vicinity of the metal (plasmon) nanoparticle is considered. It is demonstrated that the steady-state generation of spaser is pre- ceded by the regime with the oscillations at the Rabi frequency in which the phase difference between the dipole moments and the direction of the energy flux from the quantum dot to the nanoparticle exhibit the sign alternation. DOI: 10.1134/S1064226911120151