Blue Light Generation of Strongly Focused Gaussian Beams by Frequency Doubling of Nd:GSAG Laser

Frequency doubling of a focused Gaussian beam involves phase mismatching due to beam divergence. The conversion efficiency was calculated by integration second-harmonic (SH) field along the energy flow propagation path. The resulting SH field spatial distribution was discussed. We demonstrated the generation of blue light in critically type-I phase-matched LiB
₃
O
₅
by frequency doubling of a diode-pumped electrooptic
Q
-switched Nd:GSAG laser at room temperature. Pulsed blue light with 8-mJ energy and 300-ns pulse duration at 471 nm was generated with 19-mJ incident radiation at 10 Hz. The maximum conversion efficiency was 42%. The experimental results agree well with our calculations.