Abstract
In a uniaxial crystal, walk‐off or double refraction occurs only in the plane of the direction of propagation and the optic axis. By elliptical focusing of the signal, idler, and pump we can focus much more tightly in the non‐walk‐off plane and increase parametric gain considerably. Optimum focusing conditions are obtained, and in a typical LiNbO3 oscillator pumped with 1.06 μ we find that threshold can be lowered more than a factor of 5.
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