根据准相位匹配原理,对钼酸钆晶体用于准相位匹配倍频过程的周期性畴结构进行了设计,当入射基频光为1.064 μm时,所需的钼酸钆晶体畴结构周期为5.54 μm。利用外电场极化,当外电场为2.5 kV/mm时,钼酸钆晶体的畴结构反转时间tc＝500～600 μs。当外电场脉冲幅值为2.5 kV/mm、脉冲延续时间t＝0.6～0.8tc时,在钼酸钆晶体中制备得到了周期畴结构。当Nd:YAG纳秒激光器输出准连续功率为7～10 mW的1.064 μm激光通过具有周期畴结构的样品时,获得了0.532 μm的倍频光输出。

According to the theory of quasi-phase-matching (QPM), the periodical domain structure in gadolinium molybdate crystal for QPM second harmonic generation is designed. The designed domain period is 5.54 μm if the fundamental wavelength is 1.064 μm. The periodical domain structure is fabricated via poling the crystal with applied external pulse field. The switching time t c of the crystal is 500～600 μs when the external field is 2.5 kV/mm. The periodical domain structure has been obtained under the conditions that the voltage is 2.5 kV/mm and the duration of the applied pulse is 0.6～0.8t c. Using the periodically poled sample, harmonic wave of 0.532 μm has been achieved when the power of the fundamental Nd∶YAG laser is 7～10 W.