Hyyti Janne, Escoto Esmerando, Steinmeyer Günter
Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany.
Rev Sci Instrum. 2017 Oct;88(10):103102. doi: 10.1063/1.4991852.
A novel algorithm for the ultrashort laser pulse characterization method of interferometric frequency-resolved optical gating (iFROG) is presented. Based on a genetic method, namely, differential evolution, the algorithm can exploit all available information of an iFROG measurement to retrieve the complex electric field of a pulse. The retrieval is subjected to a series of numerical tests to prove the robustness of the algorithm against experimental artifacts and noise. These tests show that the integrated error-correction mechanisms of the iFROG method can be successfully used to remove the effect from timing errors and spectrally varying efficiency in the detection. Moreover, the accuracy and noise resilience of the new algorithm are shown to outperform retrieval based on the generalized projections algorithm, which is widely used as the standard method in FROG retrieval. The differential evolution algorithm is further validated with experimental data, measured with unamplified three-cycle pulses from a mode-locked Ti:sapphire laser. Additionally introducing group delay dispersion in the beam path, the retrieval results show excellent agreement with independent measurements with a commercial pulse measurement device based on spectral phase interferometry for direct electric-field retrieval. Further experimental tests with strongly attenuated pulses indicate resilience of differential-evolution-based retrieval against massive measurement noise.
提出了一种用于干涉频率分辨光学门控（iFROG）超短激光脉冲表征方法的新算法。基于一种遗传方法，即差分进化，该算法能够利用iFROG测量的所有可用信息来恢复脉冲的复电场。对该恢复过程进行了一系列数值测试，以证明该算法对实验伪像和噪声的鲁棒性。这些测试表明，iFROG方法的集成误差校正机制可成功用于消除检测中定时误差和光谱变化效率的影响。此外，新算法的准确性和抗噪声能力优于基于广义投影算法的恢复方法，该方法被广泛用作FROG恢复的标准方法。利用来自锁模钛宝石激光器的未放大三周期脉冲进行测量得到的实验数据，进一步验证了差分进化算法。在光路中额外引入群延迟色散，恢复结果与基于光谱相位干涉术直接电场恢复的商用脉冲测量装置的独立测量结果显示出极好的一致性。对强衰减脉冲进行的进一步实验测试表明基于差分进化的恢复方法对大量测量噪声具有抗性。
