Controllable polarization for passively Q-switched Nd:YAG/Cr4+:YAG laser

• We demonstrated a polarization controllable Cr4+:YAG microchip laser.
• The output polarization mainly depends on the pump polarization.
• Highly stabled and polarized output was achieved.

We demonstrated a passively Q-switched Nd:YAG/Cr4+:YAG microchip laser with high stability and highly polarized output. The output polarization mainly depends on the pump polarization by using [0 0 1]-cut Cr4+:YAG crystal as a saturable absorber. Highly stabled output was achieved when the pump polarization direction was parallel to the crystallographic axis of [0 0 1]-cut Cr4+:YAG crystal. The 1064 nm laser with the output power of 0.5 W at 20 kHz, with the pulse duration of 2.3 ns was generated. The extinction ratio was above 300:1 and the polarized output stability was higher than 96.8%.