| 摘要 |
It is the object of a device for converting a fundamental laser frequency to other frequencies to further increase the conversion efficiency in successive nonlinear processes at a low cost with respect to material and alignment and in a space-saving compact arrangement and to make use of the advantages of noncritical phase matching for this purpose. Between two nonlinear optical crystals for generating a first new frequency and for frequency mixing of a pair of laser beams which is generated in the first crystal and whose laser beams are polarized perpendicular to one another, there is arranged another birefringent crystal which is penetrated by the pair of laser beams and in which nonlinear optical characteristics are prevented, so that the pair of laser beams exits from the birefringent crystal with unchanged frequencies. One of the two laser beams, as extraordinary polarized laser beam, undergoes a walk-off in the birefringent crystal, which walk-off is directed opposite to the walk-off occurring in one of the two crystals. Devices of this kind which make use of nonlinear optical processes for frequency conversion are used particularly in solid state lasers.
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