Polarization control element and solid state laser

摘要

A polarization control element for controlling the direction of polarization and the longitudinal mode of a laser is formed by cutting a birefringent crystal so that its light incident face and light emanating face are at an angle to the optical axis of the crystal and adjusting the thickness and the reflectivities of the faces of the crystal so that the crystal can function as a Fabry-Perot etalon. The thickness of the birefringent crystal is set so that the wavelengths selected by the birefringent crystal for two laser oscillation modes whose directions of polarization are normal to each other differ from each other.