Fig. 1. Schematic diagram for measurement and analysis of linear polarization regime of passively Q-switched Nd:YAG/Cr4+:YAG laser.

Fig. 2. Output power and polarization extinction ratio (PER) as functions of the incident pump power under (a) free pump and (b) horizontal polarization pump. Insets show the polarization directions and beam profiles when the Glan prism was along the polarization directions.

Fig. 3. PER versus pump polarization angle. 0° and 90° represent horizontal and vertical pump polarization, respectively, and other angles could be deduced.

Fig. 4. Profile analyzation of the polarized beam near the extinction position, under (a)–(c) free pump and (d)–(f) horizontal polarization pump. The extinction position was defined as 0°.

Fig. 5. Polarization mechanism for (a) intrinsic state and (b) combined state.

Fig. 6. (a)–(c) Theoretically simulated results of profile analyzation near the extinction position. α represents the azimuth angle of the polarizer. The extinction position was defined as 0°.