Polaritons lasers

Zamfirescu, M., Kavokin, A., Gil., B, Malpuech, G., Kaliteevski, M. (2002). ZnO as a material mostly adapted for the realization of room-temperature polariton lasers. Physical Review B, 65, 161205(4). 

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. 

Kurtz and Giordmaine 79> were the first to observe stimulated Raman scattering at the polariton associated with the TO phonon at 630 cm-1 which was shifted to 497 cm-1 for 0° scattering excited with a Q-switched ruby laser. The corresponding phonon was also observed in this experiment. This can be explained by backward (180°) stimulated Raman scattering reflected from the laser resonator mirrors as confirmed by measurements of relative time of arrival at the spectrometer. 

The use of lasers for the excitation of Raman spectra of solids has led to the detection of many new elementary excitations of crystals and to the observation of nonlinear effects. In this review we have tried to lead the reader to a basic understanding of these elementary excitations or quasi-particles, namely, phonons, polaritons, plasmons, plasmaritons, Landau levels, and magnons. Particular emphasis was placed upon linear and stimulated Raman scattering at polaritons, because the authors are most familiar with this part of the field and because it facilitates understanding of the other quasi-particles. 

Fig. 6.13. The polariton wavepacket, created by coherent scattering of picosecond laser and Stokes pulses, propagates in the crystal at the angle 0 with respect to the excitation direction. This angle is determined by the excitation wavevector geometry (see above). The coherent amplitude of the propagating wavepacket may be measured by phase-matched coherent anti-Stokes scattering of a probe pulse suitably delayed in time (fn) and displaced in space (by Xn)- Reprinted with permission from Gale et al. (68). Copyright (1986), American Physical Society.

Fig. 6.13 The polariton wavepacket, created by coherent scattering of picosecond laser and Stokes pulses 207...

If an incident laser light Eo interacts with the metal nanosphere, a collective movement of the electrons against the atomic cores of the metals - a so-called surface plasmon - is induced. The interaction of the surface plasmons and the incident laser light causes the so-called localized surface plasmon polaritons, resulting in an evanescent electromagnetic field E y, which is emitted fi-om the nanoparticle. The signal intensity achieved for SERS depends on the absolute square of the emitted field Egy, which can be simplified written as follows ... 

Figure 1(a) shows the Kretschmann configuration [9] for the excitation of plasmon surface polaritons (surface plasmons for short) [10] in the attenuated total reflection (ATR) mode. When a p-polarized laser beam is irradiated at the (internal) incident angle 9t from the prism of a refractive index np above 6c, a strong nonradiative electromagnetic wave, i.e. a surface plasmon is excited at the resonant angle which propagates at the metal /electrolyte interface. 

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