Patent ID: 7542490

Claim:
A device for generating a frequency converted laser beam, the device comprising: a nonlinear crystal having a first end face and a second end face opposed to the first end face, wherein the nonlinear crystal is configured to receive at least one input laser beam at the first end face and output a frequency converted beam at the second face, wherein a beam waist of the at least one input laser beam is positioned between the first end face and the second end face during a frequency conversion process; and a second crystal having a first end face bonded to the second end face of the nonlinear crystal and a second end face opposed to the first end face, wherein a beam diameter of the frequency converted beam at the first end face of the second crystal is less than a beam diameter of the frequency converted beam at the second end face of the second crystal, wherein the nonlinear crystal and the second crystal comprise a same nonlinear crystal material and the second crystal has an orientation deviated from a phase matching condition to thereby to reduce a magnitude of the frequency conversion process in the second crystal.