Efficient Generation of Squeezed Light Based on MgO-Doped Periodically Poled LiNbO₃

We demonstrate a high-efficiency green light conversion from an external cavity second harmonic generation with a MgO-doped periodically poled LiNbO₃ crystal. The frequency doubler can reach a conversion efficiency of 64% with a fundamental power of 26 mW. Meanwhile, the generated green light is quadrature-amplitude squeezed and 1.2 dB green light squeezing is experimentally measured. The squeezing at different pump levels is also investigated and is in good agreement with the theoretical prediction.