  Polarization analyses of the terahertz (THz) emission from
Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ whisker crystals used for
superconducting THz emitters were conducted. The THz emission mode was
estimated by a simple polarization measurement, and a simulation study was
conducted to examine the validity of the polarization analysis. The refractive
index of whisker crystals revealed through the polarization analyses was
greater than that of bulk single crystals and agreed well with our previous THz
emission report. The simulation study suggested the complex plasma excitation
mode of the THz emission, and an interpretation of the refractive index
obtained in this study is provided.
