Frequency-converted high-power laser with recirculating polarization control

Abstract

A frequency-tripled laser-resonator has three resonator-branches. The branches are optically connected with each other by one or more polarization-selective devices. Unpolarized fundamental radiation is generated by optically pumping a gain-element in one branch of the resonator. The polarization-selective device provides that radiation in the other branches is plane-polarized, with the polarization planes of radiation entering the branches perpendicular to each other. Two optically nonlinear crystals are located in one of the branches of the resonator in which the fundamental radiation is plane-polarized and arranged to generate third-harmonic radiation. Three-branch resonators including two gain-elements having a optical relay therebetween, and a three-branch ring-laser-resonator are also disclosed.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates in general to intracavity frequency-converted, diode-pumped, solid-state lasers. The invention relates in particular to such lasers having a gain-medium optically pumped at a power high enough to cause thermal-birefringence in the gain-medium sufficient that fundamental-wavelength radiation generated in the laser is unpolarized.DISCUSSION OF BACKGROUND ART[0002]In a laterally diode-pumped, solid-state laser, such as a laser having a resonator including a neodymium-doped yttrium aluminum garnet (Nd:YAG) gain-medium, laser pump-power can be raised to a level at which thermally induced birefringence in the Nd:YAG gain-medium can cause fundamental-wavelength radiation circulating in the resonator to be unpolarized. The radiation can not be caused to be polarized without considerable loss of efficiency of generating the radiation.[0003]Unpolarized fundamental-wavelength radiation can be frequency-doubled in an optically ...

AI Technical Summary

Benefits of technology

[0007]In yet another aspect, a laser in accordance with the present invention comprises a ring laser-resonator having first, second, and third branches. At least one gain-element and a fractional-wave plate are located in the third branch of the resonator. An arrangement is provided for optically pumping the gain-element such that laser radiation having a fundamental wavelength circulates in the laser-resonator. An optical diode is positioned in one of the first and second resonator-branches such that the fundamental-wavelength radiation circulates in only one direction in the laser-resonator. First and second polarization-selective devices optically connect the first and second separate branches of the resonator to the third branch of the resonator. The laser-resonator, the fractional-wave plate, and the one or more polarization-selective devices are arranged such that fundamental-wavelength radiation in the first and second resonator-branches is polarized in respectively first and second orientations perpendicular to each other.

Problems solved by technology

The radiation can not be caused to be polarized without considerable loss of efficiency of generating the radiation.

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