  We have systematically investigated the optical properties of the InP1-xBix
ternary alloys with 0<x<2.46%, using high resolution polarized Raman scattering
measurement. Both InP-like and InBi-like optical vibration modes (LO) were
identified in all the samples, suggesting most of the Bi-atoms are incorporated
into the lattice sites to substitute P-atoms. And the intensity of the
InBi-like Raman modes increase exponentially as Bi-content increasing. Linearly
red-shift of the InP-like longitudinal optical vibration modes was observed to
be 1.1 cm-1 of percent Bi, while that of the InP-like optical vibration
overtones (2LO) were nearly doubled. In addition, through comparing the
difference between the Z(X,X)Z and Z(X,Y)Z Raman spectra, Longitudinal Optical
Plasmon Coupled (LOPC) modes are identified in all the samples, and their
intensities are found to be proportional to the electron concentrations.
