Kim Eok Bong, Lee Jae-Hwan, Lee Won-Kyu, Luu Tran Trung, Nam Chang Hee
Dept of Physics and Coherent X-ray research Center, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
Opt Express. 2010 Dec 6;18(25):26365-72. doi: 10.1364/OE.18.026365.
The long-term carrier-envelope phase (CEP) coherence of a femtosecond laser with same pulse-to-pulse CEP value, obtained using the direct locking method, is demonstrated by employing a quasi-common-path interferometer (QPI). For the evaluation of the CEP stability, the phase noise properties of a femtosecond laser with the CEP stabilized using a QPI are compared with those obtained using a Mach-Zehnder f-2f interferometer, for which the phase power spectral density and the Allan deviation were calculated from the beat signals of the interferometers. With the improved CEP stability, the long-term CEP coherent signal with an accumulated phase noise well below 1 radian can be maintained for more than 56 hours, i.e., the CEP coherence is preserved without a phase cycle slip for more than 1.6 × 10(13) pulses at a repetition rate of 80 MHz. The relative stability is also estimated to be approximately 1.4 × 10(-22) at a central wavelength of 790 nm.
通过使用准共路干涉仪（QPI），证明了采用直接锁定方法获得的具有相同脉冲间载波包络相位（CEP）值的飞秒激光的长期载波包络相位相干性。为了评估CEP稳定性，将使用QPI稳定CEP的飞秒激光的相位噪声特性与使用马赫曾德尔f-2f干涉仪获得的相位噪声特性进行了比较，从干涉仪的拍频信号计算出相位功率谱密度和阿伦偏差。随着CEP稳定性的提高，累积相位噪声远低于1弧度的长期CEP相干信号可以保持超过56小时，即在80 MHz的重复频率下，超过1.6×10(13)个脉冲的CEP相干性得以保持，没有相位循环滑移。在790 nm的中心波长处，相对稳定性估计约为1.4×10(-22)。
