Experimental Techniques

This chapter summarizes some of the experimental techniques that can be used to study polariton excitations in periodic and quasiperiodic structures. The techniques that are presented in the chapter include Raman scattering, Brillouin light scattering (BLS), and resonant Brillouin scattering (RES). The first application of Raman scattering to plasmons in periodic superlattices was for measurements on doped GaAs/Ala x Ga 1-x As superlattices. The modes corresponded fairly well to the model with 2D charge sheets. It is known that spectra are sensitive to the quasiperiodic structure of the superlattice as well as the phonon properties. The observed acoustic frequencies are shifted depending on the size or stage number of the lattice. By contrast, periodic superlattices typically exhibit peak broadening in similar-sized structures. As in the case of Raman scattering, BLS provides a well-established, non-destructive optical technique. It can yield a great deal of information about magnetism in low-dimensional systems such as thin films, multilayers, and patterned structures. Also, BLS gives information about the dynamical properties of a spin system through the detection of long-wavelength spin waves. RBS is perhaps the most powerful experimental technique to probe exciton-polaritons.