Polariton

Kawata, S. (2001) Neur-Fidd Optics and Surface Plasmon Polaritons, Springer, Heidelberg. 

One of the applications of TRXRD is to study complex systems where electric fields couple to multiple degrees of freedom. Though femtosecond laser pulses can generate THz radiation from ferroelectric LiTa03, the corresponding lattice motion remained undetected by optical measurements. Cavalleri and coworkers demonstrated the coherent modulation of the X-ray intensity at 1.5 THz [10], and assigned it as phonon-polariton mode of A symmetry (Fig. 3.3). Nakamura and coworkers detected the coherent LO phonon of CdTe... 

The intriguing properties of devices made by the combination of a film-forming dye and an optical microstructure turn up in the discovery of strong coupling between excited states and photon modes in microcavities, creating Rabi-splitted polariton modes [211]. They occur in materials with narrow absorption bands (e.g., porphyrins and cyanine dyes) and may pave the way to new laser types and fundamental insights into the interaction of matter and light. 

T. Tamir, J. J. Burke, and G. I. Stegeman, Surface polariton-like waves guided in thin, lossy metal films, Phys. Rev. B 33, 5186-5201 (1986). 

Surface plasmon-polaritons (SPP), also referred as to surface plasma waves, are special modes of electromagnetic field which can exist at the interface between a dielectric and a metal that behaves like a nearly-iree electron plasma. A surface plasmon is a transverse-magnetic mode (magnetic vector is perpendicular to the direction of propagation of the wave and parallel to the plane of interface) and is characterized by its propagation constant and field distribution. The propagation constant, P can be expressed as follows ... 

Figure 3. Optical excitation of surface plasmon-polaritons (surface plasmon) by the attenuated...

TMM handles thin metallic films as well, as they are used in lO-sensors based on surface-plasmon-polaritons (SPP). SPPs appear at the dielectric-metal interface for TM polarization, exclusively. The sensor principle is to have a waveguide mode and the SPP close to resonance, and screen the resonance vs. angle or vs. wavelength to detect refractive index changes of the cladding. Figure 4 shows the resonance of the absorption vs. the... 

When a metallic probe, which has a nanometric tip, is illuminated with an optical field, conductive free electrons collectively oscillate at the surface of the metal (Figure 10.3). The quantum of the induced oscillation is referred to as surface plas-mon polariton (SPP) (Raether 1988). The electrons (and the positive charge) are concentrated at the tip apex and strongly generate an external electric field. Photon energy is confined in the local vicinity of the tip. Therefore, the metallic tip works as a photon reservoir. 

It has been shown that a metallic probe tip highly localizes and strongly amplifies the optical field throngh the resonance effect of the plasmon polaritons at the probe tip. This concept has made it possible to optically observe nanometric samples with a nanometric spatial resolntion. 

Hayazawa, N., Ishitobi, H., Taguchi, A., Ikeda, K., Tarun, A., and Kawata, S. 2007a. Focused excitation of surface plasmon polaritons for efhcient held enhancement based on gapmode in tip-enhanced spectroscopy. Jpn. J. Appl. Phys. 46 7995-99. 

Kawata, S. 2001. Near-field optics and surface plasmon polaritons. New York Springer. 

Ions in the lattice of a solid can also partake in a collective oscillation which, when quantized, is called a phonon. Again, as with plasmons, the presence of a boundary can modify the characteristics of such lattice vibrations. Thus, the infrared surface modes that we discussed previously are sometimes called surface phonons. Such surface phonons in ionic crystals have been clearly discussed in a landmark paper by Ruppin and Englman (1970), who distinguish between polariton and pure phonon modes. In the classical language of Chapter 4 a polariton mode is merely a normal mode where no restriction is made on the size of the sphere pure phonon modes come about when the sphere is sufficiently small that retardation effects can be neglected. In the language of elementary excitations a polariton is a kind of hybrid excitation that exhibits mixed photon and phonon behavior. 

Infrared Ellipsometry on Semiconductor Layer Structures Phonons, Plasmons, and Polaritons... 

The elementary excitations mentioned so far are not related in any special way to the solid state and will therefore not be treated in this article. We will discuss here the following low-lying quantized excitations or quasi-particles which have been investigated by Raman spectroscopic methods phonons, polaritons, plasmons and coupled plasmon-phonon states, plasmaritons, mag-nons, and Landau levels. Finally, phase transitions were also studied by light scattering experiments however, they cannot be dealt with in this article. 

When the power of the exciting radiation is raised into the megawatt range, nonlinear Raman effects are observed, namely the stimulated Raman effect, the inverse Raman effect (Stoicheff absorption), and the hyper-Raman effect. The results of such experiments with single crystals will be discussed in the last chapter, with special emphasis on stimulated Raman scattering from polaritons. 

A. Long-Wave Optical Phonons and Polaritons 1. Longitudinal Optical and Acoustical Phonons... 

This is the background for the Lyddane-Sachs-Teller relation to be treated below. For transverse optical vibrations the origin of an is field is less obvious, but it is also present and its reaction on the eigenfrequency of the TO phonon later gives rise to the polaritons. 

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