Enhanced spontaneous emission

Komarala, V. K., Rakovich, Y. P., Bradley, A. L., Byrne, S. J, Gun ko, Y. K., Gaponik, N. and Eychmuller, A. (2006). Off-resonance surface plasmon enhanced spontaneous emission from CdTe quantum dots. Appl. Phys. Lett. 89 253118. 

Chen J., Shen N.H., Cheng C., Fan X.Y., Ding J.J. and Wang H.T., (2006) Tunable resonance in surface-plasmon-polariton enhanced spontaneous emission using a denser dielectric cladding, Appi. Phys. Lett. 89 051916 Paiella R., (2005) Tunable surface plasmons in coupied metaiio-dieiectric muitiple layers for light-emission efficiency enhancement, Appi. Phys. Lett. 87 111104(2005). 

The presence of the additional damping terms F12 may suggest that quantum interference enhances spontaneous emission from two coupled systems. However, as we shall illustrate in the following sections, the presence of these terms in the master equation can, in fact, lead to a reduction or even suppression of spontaneous emission. According to Eq. (62), the reduction and suppression of spontaneous emission can be controlled by changing the mutual orientation of the dipole moments of the bare systems. 

The subject of correlated or collective spontaneous emission by a system of a large number of atoms was first proposed by Dicke [1], who introduced the concept of superradiance that the influence on each atomic dipole of the electromagnetic field produced by the other atomic dipoles could, in certain circumstances, cause each atom to decay with an enhanced spontaneous emission rate. The shortening of the atomic lifetime resulting from the interaction between N atoms could involve an enhancement of the intensity of radiation up to N2. 

Yablonovitch E., Gmitter T. J., Bhat R. Inhibited and enhanced spontaneous emission from optically thin AlGaAs/ GaAs double heterostructures Phys. Rev. Lett. 61, 2546 (1988). 

Yokoyama H., Nishi K., Anan T., Yamada H., Boorson S.D., Ippen E. P. Enhanced spontaneous emission from GaAs quantum wells in monolithic microcavities Appl. Phys. Lett. 57, 2814 (1990). 

The coherent emission intensity of an ensemble of N molecules is therefore N times stronger than the incoherent emission. This result is due to the N(N— 1) cross-terms in the expansion as first shown by Dicke. A closer look at this enhanced spontaneous emission shows that the coherent emission is also highly directional, in fact in a sample of macroscopic size the constructive interference effects only occur in the direction of the exciting laser beam. 

Enhanced spontaneous emission of radiation from Rydberg atoms was reported in 1983 by Goy et al.t59], in this experiment excited sodium atoms (in the 23S state) were formed within a superconducting cavity resonant at 3 0 GHz. This frequency closely corresponds to the... 

Since a resonant cavity can enhance spontaneous emission, it is not surprising that a nonresonant cavity can depress it. Consider for instance a cavity whose fundamental frequency is at twice the resonant frequency of the atomic transition. In this case, the radiation rate becomes... 

Both regimes (i) and (ii) have been recently investigated the enhanced spontaneous emission effect which requires cavities of relatively moderate Q (y 10 ) has been observed by Goy et al. in 1983 . The oscillatory exchange of photon between the atom and the cavity requires larger Q s (y 10 ) and is just now in the process of being directly observed by Walther and Rempe . 

M Boroditsky, R Vrijen, TF Krauss, R Coccioli, R Bhat, and E Yablonovitch, Spontaneous emission extraction and Purcell enhancement from thin-film 2-D photonic crystals, J. Lightwave Technol., 17 2096-2112, 1999. 

Sponge consolidation, in titanium manufacture, 24 854 Spontaneous emission, 14 848-850 Spontaneous emission enhancements, 14 855... 

Figure 7. Difference in the spontaneous emission enhancement in a LED (a) and a microcavity laser (b) Density of electronic states in bulk semiconductor material and lowdimensional semiconductor heterostructures (c).

Clearly, to increase the enhancement factor, it is necessary to design and fabricate high-Q, small-V microresonators. However, cavity-enhanced LEDs based on the microresonators with high-Q modes must have equally narrow material spontaneous emission linewidths (Fig. 7a), which are not easily realized in bulk or heterostructure quantum-well microresonators. The recently proposed concept of an active material system, semiconductor quantum dots (QDs) (Arakawa, 2002) combines the narrow linewidth... 

If an atomic transition is optically pumped by a beam of laser radiation having the appropriate frequency, the population in the upper state can be considerably enhanced along the path of the beam. This causes an intensification of the spontaneous emission from this state, which contains information about the conditions within the pumped region, since the exponential decay time for the intensified emission depends upon both the electron number density and the electron temperature. The latter can be obtained from the intensity ratio of the fluorescence excited from two different lower levels, if local thermal equilibrium is assumed. This method has been dis-... 

Spontaneous emission and absorption probability is enhanced by the factor... 

The procedure that we propose to enhance the concentration of a particulap enantiomer when starting with a racemic mixture, that is, to purify the mixture) is as follows [259], The mixture of statistical (racemic) mixture of L and irradiated with a specific sequence of three coherent laser pulses, as described below. These pulses excite a coherent superposition of symmetric and antisymmetric vibrational states of G. After each pulse the excited system is allowed to relax bg t to the ground electronic state by spontaneous emission or by any other nonradiativ process. By allowing the system to go through many irradiation and relaxatio cycles, we show below that the concentration of the selected enantiomer L or can be enhanced, depending on tire laser characteristics. We call this scenario lat distillation of chiral enantiomers. 

Le Ru, E. C., and Etchegoin, P. G. (2005). Surface-Enhanced Raman Scattering (SERS) and Surface-Enhanced Fluorescence (SEF) in the context of modified spontaneous emission. arXiv physics/0509154vl pp.1-14. 

The Purcell s original idea [10] on modification of photon spontaneous emission rate is extended to modification of photon spontaneous scattering rate. Simultaneous account for local incident field and local density of photon states enhancements in close proximity to a silver nanoparticle is found to provide up to lO -fold Raman scattering cross-section rise up. Thus, single molecule Raman detection is found to be explained by consistent quantum electrodynamic description without chemical mechanisms involved. 

Surface enhanced fluorescence (SEE) takes place in the proximity of metal structures. The effect of fluorescence enhancement has been intensively studied by several groups [74]. In the proximity of metals, the fluorophore radiative properties are modified and an increase in the spontaneous emission rate is observed. 

An example of entangled states in a two-atom system are the symmetric and antisymmetric states, which correspond to the symmetric and antisymmetric combinations of the atomic dipole moments, respectively [1,7,21]. These states are created by the dipole-dipole interaction between the atoms and are characterized by different spontaneous decay rates that the symmetric state decays with an enhanced, whereas the antisymmetric state decays with a reduced spontaneous emission rate [7]. For the case of two atoms confined into the region much smaller than the optical wavelength, the antisymmetric state does not decay at all, and therefore can be regarded as a decoherence-free state. 

The master equation (38) provides the simplest example of the effects introduced by the coherent interaction of atoms with the radiation field. These effects include the shifts of the energy levels of the system, produced by the dipole-dipole interaction, and the phenomena of enhanced (superradiant) and reduced (subradiant) spontaneous emission, which appear in the changed damping rates to (T + Ti2) and (T — Ti2), respectively. 

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