| 主权项 |
1. Laser apparatus, comprising:
a gain-element in the form of a rare-earth-doped, prismatic, birefringent crystal having first, second, third faces parallel to the c-axis of the crystal and at an angle to each other, the gain-element having polarization-dependent gain strongest in the c-axis direction; a source of pump-radiation for energizing the gain-element, thereby causing the gain-element to emit laser-radiation at the fundamental wavelength and plane-polarized in the c-axis direction of the gain-element; a laser-resonator for the c-axis polarized fundamental-wavelength radiation, the resonator formed between a first end-mirror, and one of (1) a coating on the third face of the prism highly reflective at the fundamental emission wavelength of the crystal, and (2) a second end-mirror spaced apart from the third face of the prism; a polarization-rotator located in the resonator and arranged to selectively rotate the polarization of radiation making a double-pass therethrough; and wherein when the polarization is rotated by the polarization-rotator at a non-orthogonal angle to the c-axis direction, the radiation is resolved into a c-axis polarized component and an a-axis polarized component polarized perpendicular to the c-axis direction, with the c-axis polarized radiation circulating in the laser-resonator and the a-axis component of the radiation being transmitted through the second face of the gain-element as output radiation wherein the polarization-resolved radiation is non-normally incident on the first face of the prism and the c-axis polarized component and the a-axis polarized component follow separate paths in the crystal at an angle to each other. |
