Abstract: A second harmonic generator (SHG) for generating second harmonics from a non-linear bifringent crystalline material of a resonator utilizes a brewster plate within the laser cavity instead of a conventional beam splitter, and part of split second harmonics is used for controlling the temperature of the non-linear bifringent crystalline material. Thus, due to the elimination of the conventional beam splitter, the overall size of a manufactured SHG module can be reduced by about 20%, and the utilization of nearly 100% of the generated harmonics is made possible without any loss in the beam splitter. Further, since the beam splitter is eliminated, beam loss and beam quality deterioration due to beam interference within the conventional beam splitter may be avoided.