Apparatus and method for frequency conversion and mixing of laser light

A method and device for the nonlinear combination of laser light which produces a beam of uniform intensity, high spatial purity, and high conversion efficiency. The method includes emitting a laser light from a tunable distributed feedback fiber laser having both thermal and piezoelectric control elements which produces a laser light at a given frequency, wavelength, and intensity, converting the laser light in a nonlinear resonator which uses a nonlinear optical crystal for frequency conversion or mixing; and measuring the resonant frequency of the nonlinear resonator and adjusting the laser light frequency using both the thermal and piezoelectric elements of the fiber laser light source to match the resonant frequency conditions within the nonlinear resonator.