The 2 oscillator circuits under are suitable for employing crystal oscillators in series or parallel method: Higher-repetition-fee and high-electrical power picosecond regenerative amplifier based upon just one bulk Nd:GdVO4 crystal 中原子或分子的排列具有三维空间的周期性，隔一定的距离重复出现，这种周期性规律是 A significant ability passively mode-locked picosecond oscillator according... https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html