Ma Cheng, Xu Xiao, Wang Lihong V
Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130-4899, USA.
Sci Rep. 2015 Mar 10;5:8896. doi: 10.1038/srep08896.
Recent breakthrough in wavefront engineering shows great promises in controlling light propagation inside scattering media. At present, the digital approaches enjoy high gain, while their speeds are slow because of high data throughputs. In contrast, the analog approaches are intrinsically fast but suffer from poor efficiencies and small gains. Further improvements in both speed and gain are necessary to advance the existing technologies toward real-world applications. Here, we report analog time-reversal of acousto-optically tagged photons with a flux amplification of over 33,000 times (45 dB) at a target location inside scattering media. Such a substantial power gain enhancement is achieved when the temporal width of the time-reversed photon packet is squeezed below the carrier-recombination-limited hologram decay time in a photorefractive crystal. Despite a focusing energy gain below unity, the unprecedented power gain is expected to enable new optical imaging, sensing, manipulation and treatment applications.
波前工程领域的最新突破在控制光在散射介质中的传播方面展现出了巨大潜力。目前，数字方法增益高，但由于数据吞吐量高，速度较慢。相比之下，模拟方法本质上速度快，但效率低且增益小。要推动现有技术走向实际应用，速度和增益都需要进一步提高。在此，我们报告了在散射介质内部的目标位置对声光标记光子进行模拟时间反转，通量放大超过33000倍（45分贝）。当时间反转光子包的时间宽度被压缩到低于光折变晶体中载流子复合限制的全息图衰减时间时，就实现了如此显著的功率增益增强。尽管聚焦能量增益低于1，但这一前所未有的功率增益有望实现新的光学成像、传感、操纵和治疗应用。
