Goy Alexandre S, Makris Konstantinos G, Psaltis Demetri
Opt Express. 2015 Jan 12;23(1):431-44. doi: 10.1364/OE.23.000431.
In focusing Kerr media, small-scale filamentation is the major obstacle to imaging at high light intensities. In this article, we experimentally and numerically demonstrate a method based on statistical averaging to reduce the detrimental effects of filamentation on the reconstructed images. The experiments are performed with femtosecond optical pulses propagating through a nonlinear liquid (toluene). We use digital holography to capture the transmitted optical image. The reverse propagation of the captured field is numerically performed using a numerical solution of the nonlinear Schrödinger equation. Because of their intrinsic sensitivity to measurement noise, filaments fail to propagate back on their initial trajectories and parasitic filaments form. The principle of the method is the introduction of artificial perturbations on the measurement, which spatially displace the parasitic filaments. By averaging the reconstruction over many realizations of the artificial perturbation, we show that the reconstruction improves the quality of the images. Finally, in order to identify the different regimes of optical power for which the filaments are time reversible, we also derive an analytical estimate for the condition number of the nonlinear propagator.
在聚焦克尔介质中，小尺度丝状化是高光强成像的主要障碍。在本文中，我们通过实验和数值模拟证明了一种基于统计平均的方法，以减少丝状化对重建图像的有害影响。实验使用飞秒光脉冲在非线性液体（甲苯）中传播进行。我们使用数字全息术来捕获透射光学图像。利用非线性薛定谔方程的数值解对捕获场进行数值反向传播。由于细丝对测量噪声具有固有敏感性，它们无法沿初始轨迹反向传播，并且会形成寄生细丝。该方法的原理是在测量中引入人工扰动，使寄生细丝在空间上发生位移。通过对人工扰动的多次实现进行重建平均，我们表明重建提高了图像质量。最后，为了确定细丝时间可逆的不同光功率范围，我们还推导了非线性传播器条件数的解析估计。
