A device for generating a frequency converted laser beam includes a
nonlinear crystal having a first end face and a second end face opposed
to the first end face. 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. 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. The device also includes 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. 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.