(color online) Schematic diagrams of three typical polarization configurations for angle-resolved polarized Raman spectroscopy: (a) and , (b) and , and (c) and , in which the polarizer is set in the beam path to make the incident laser to be vertically polarized. The analyzer before the spectrometer entrance selects vertically or horizontally polarized Raman signal to be detected. The half-wave plate is used to change the polarization direction of laser or signal. Laboratory coordinate(xyz) is represented by black arrows while crystal coordinate ( ) is represented by gray arrows. Red two-way arrows stand for the incident laser polarization reaching at sample. The blue two-way arrows represent the original polarization of Raman signal corresponding to vertically or horizontally polarized signal selected by the analyzer before spectrometer entrance.