Photon localization

Fig. 14.7. High resolution Raman spectrum for D20 excited with a 171 nm photon. Local mode assignment is used the first two quantum numbers indicate the OH stretching modes, the plus sign indicates the symmetry, and the third number represents the bending quantum number. The latter is zero in all cases and therefore not mentioned in the text. The energies are measured with respect to the 00+0) vibrational ground state. Reproduced from Sension et al. (1990).

We now stress that, in the usual treatment of photon localization, the radiation field is considered as though it consist of the plane waves of photons [14-20]. In reality, the radiation emitted by the atomic transitions corresponds to the multipole photons [23] represented by the quantized spherical waves [2]. 

While the simplified picture based on the model of plane waves of photons, neglecting the presence of sources and absorbers, is incapable of describing the photon localization, we show here that the use of the rich physical properties of multipole photons leads to an adequate description of localization in the atom-... 

Thus, the picture of measurement in the atom-detector system of two identical atoms is compatible with Mandel s operational approach to the photon localization. For example, the multipole photon statistics in finite volume can be examined in the same way as in Refs. 14 and 20. The commutators for different t can also be constructed in analogy to Ref. 20. 

The photon localization at detection leads to a strong increase of the vacuum noise in a certain vicinity of a detector (atom or active area of photodetector). 

The local representation of multipole photons is compatible with the Mandel operational definition of photon localization [20]. In addition to the localization at photodetection, it permits us to describe a complete Hertz-type experiment with two identical atoms used as the emitter and detector (Section VI.A). Although the photon path is undefined from the quantum-mechanical point of view, the measurement process in such a system obeys the causality principle (Section IV.B). The two-atom Hertz experiment can be realized for the trapped... 

The dissociation has been studied photochemically by exciting the dipole active HN stretch with infrared multiphoton pumping and with one-photon local mode overtone excitation. From the discussions above, it is clear that we are primarily concerned in this chapter with the vibrational events which produce the activation of the N-N reaction coordinate and not with the electronic events which determine whether the curve crossing occurs. Hence, we have focused on the events on the ground electronic surface of the parent molecule which lead to an extension of the N-N bond to 3.5a . 

From close inspection of the image, it is found that the highest enhancement occurs at the isolated dimer (A), and the enhancement observed at the rim or at the defect sites in the assembly is lower. This observation implies that the enhancement is the highest in the dimer and becomes lower with increasing size of the assembly. The finding may have some correlation with the relatively low SERS enhancement reported in close-packed assemblies. Plasmon localization at the rim of the assembly may have some similarities with photon localizations at the boundaries of photonic... 

Photons Localized, massless bundles traveling at the speed of fight with energy proportional to their frequency. 

Another feature of the PhC is photonic localization (Maloshtan and Kilin 2007). By introducing certain defects into PhCs, their existing periodicity or symmetry will be destroyed. When this happens, a rather narrow defective state occurs within the PBG, and corresponding photons would be confined to defect. In other words, by locally breaking the period into PhC, one can introduce a photonic defect mode within the bandgap and, as a result, the transmission spectrum has a relatively sharp transmission peak (see Fig. 6.3b). For example, a PhC microcavity can be formed by removing a... 

For isotropic environment, it is possible to introduce the photon local density of states (LDOS) ... 

The photon localization and enhancement effects of plasmonics can also be applied to amplify photochemical reactions, luminescence from LEDs [93], and the efficiency of solar cells [94]. DUV plasmonics is now a hot topic, since it is deeply related to environmental and energy generation issues (Chap. 9). 

With the aid of photon localization and enhancement by DUV-LSPR [59-61] LSPR, the output power of LEDs is expected to improve [62-65]. Huang et al. demonstrated for the first time that the enhanced emission of DUV-LEDs coupled to LSPRs generated by Al nanoparticles prepared on quantum wells (QWs) [66, 67]. Size- and density-controlled Al nanoparticles were fabricated by OAD (see Sect. 9.1) on the surface of Al cGai cN (x = 0.25), used as an active layer (see Fig. 9.6). Figure 9.7 shows the emitted electroluminescence (EL) spectra of samples with and without Al nanoparticles and the enhancement ratio that represents their relative intensities under a 15-mA injection current. Figure 9.7a, b shows the top emission (epitaxial layer side) and bottom emission(sapphire substrate side), respectively. A maximum tenfold top-emission enhancement and a maximum 2.8-fold bottom-emission enhancement were... 

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