Improvement of the output beam polarization of a monomode CW 119 μm H 2O vapor laser∗

This paper reports on a technique developed to fix the polarization of the output beam of a CW 119 μm H ₂O laser, oscillating in its fundamental mode. A few parallel thin metallic wires stretched inside the cavity, normal to its axis, cause the electric field to align itself perpendicular to the wires. Testing of various configurations leads to an optimum device corresponding to 94% polarization, with a laser power reduction of only 12% due to the presence of the wires.