KAIST Institute for Optical Science and Technology and School of Mechanical, Aerospace and Systems Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, South Korea.
Opt Lett. 2012 Jul 15;37(14):2958-60. doi: 10.1364/OL.37.002958.
We synchronize an 8.06 GHz microwave signal from a voltage-controlled oscillator with an optical pulse train from a 77.5 MHz mode-locked Er-fiber laser using a fiber-based optical-microwave phase detector. The residual phase noise between the optical pulse train and the synchronized microwave signal is -133 dBc/Hz (-154 dBc/Hz) at 1 Hz (5 kHz) offset frequency, which results in 838 as integrated rms timing jitter [1 Hz-1 MHz]. The long-term residual phase drift is 847 as (rms) measured over 2 h, which reaches 4×10(-19) fractional frequency instability at 1800 s averaging time. This method has a potential to provide both subfemtosecond-level short-term phase noise and long-term phase stability in microwave extraction from mode-locked fiber lasers.
我们使用基于光纤的光微波相位探测器，将一个压控振荡器产生的 8.06GHz 微波信号与一个来自 77.5MHz 锁模掺铒光纤激光器的光脉冲序列进行同步。在 1Hz（5kHz）偏移频率下，光脉冲序列和同步微波信号之间的剩余相位噪声为-133dBc/Hz（-154dBc/Hz），这导致集成 rms 定时抖动为 838as[1Hz-1MHz]。在 2 小时的测量中，长期剩余相位漂移为 847as（rms），在 1800s 的平均时间内达到 4×10(-19)分数频率不稳定度。这种方法有可能在从锁模光纤激光器中提取微波时，同时提供亚飞秒级的短期相位噪声和长期相位稳定性。
