Intracavity frequency doubling of a diode-pumped 946-nm Nd:YAG laser with bulk periodically poled MgO–LiNbO_3

We report what we believe is the first cw quasi-phase-matched intracavity frequency doubling of a diode-pumped 946-nm Nd:YAG laser by use of bulk periodically poled MgO–LiNbO₃. A maximum second-harmonic power of 5.9 mW was obtained at a laser diode power of 500 mW. The blue beam profile showed a TEM₀₀ single spatial mode of low ellipticity (1:1) because there was no walk-off problem. Bulk periodic domain inversion was accomplished by a corona discharge method with a first-order modulation period of 4.75 $\mathit{\mu }\mathrm{m}$ for a wavelength of 946 nm over a 2-mm interaction length in Z-cut 0.4-mm-thick MgO–LiNbO₃.