通过光纤使用波前整形多个信号的传输
Summary
We demonstrate the transmission of multiple independent signals through a multimode fiber using wavefront shaping employing a single spatial light modulator. By modulating the wavefront for each signal individually, spatially separated foci are transmitted. Potential applications are multiplexed data transfer in communications engineering and endoscopic light delivery in biophotonics.
Abstract
多个独立的光信号通过一个多模光纤传输用波前整形，以便在光纤内的传播过程中的光失真进行补偿来实现。我们的方法是基于采用仅单个空间光调制器，其中，所述光学波前单独的调制器的不同区域进行调制，每个光信号的一个区域的数字光学相位共轭。数字光学相位共轭的方法都被认为是比其他波前成形方法，其中（例如）进行光纤的波传播行为的完整判定更快。与此相反，所提出的方法是时有效，因为它仅需要每个光信号的一个校准。该方法可能是适合于通信工程空分复用。进一步的应用领域是生物光子学内镜光传输，特别是在邻ptogenetics，其中单细胞生物组织有以高空间和时间分辨率被选择性地照明。
Introduction
多个光信号通过一多模光纤（MMF）的传输是在通信工程1和生物光子学2明显。在通信工程，空间多路复用（SDM）被认为是为了增强对未来的数据传输应用的光纤的传输容量从在有限的空间的利用率更高受益，一个可行的解决方案相比，多个单模光纤3。在生物光子学，生物样品是由透光通过MMF内窥镜4操纵。例如，使用MMF内窥镜单个神经元的独立的光学控制是用于光遗传学兴趣为了研究神经元网络中的大脑5。然而，投射到该MMF输入面的光的传播到outpu期间受到失真由于模式混合和分散MMF的效应的T方面。其结果是，光传播被改变，这使得信号传输有挑战性。
波前成形方法6,7在散射使用空间光调制器（SLM）的媒体应用并启用对失真补偿由于在光传播8飞散。有迹象表明，优化使用光学反馈9输出迭代的方法。这些方法是相当耗时，因为有必要为许多迭代和自由度高的，相应于大量调制器元件。另一种方法是完全确定通过其传输矩阵10描述该MMF内的失真。如果要发送的模式的数目是大的，这将是耗时的，因为良好。与此相反，数字光相位共轭（DOPC）被认为是快速和这里有利的，因为只有少数焦斑有在该MMF的输出面中产生。相位共轭方法也被证明用于聚焦或成像通过生物组织12，13，14。
到目前为止，DOPC被用于一个单一的时间信号仅15，16，并通过一个MMF 17施加的光的传输。多个独立信号A DOPC方法尚未实现。我们已经开发了一种增强的方法DOPC使用提供个人波前整形采用单相仅SLM 18的每个信号多个光信号独立传输。到这个目的，在SLM被分段成区域，每个信号来传送。所提出的实验装置如图1所示，其中校准是在实际传输之前执行在b）中发生的）。
图1：实验装置。 BS =分光镜，CCD =电荷耦合器件，OM =光调制器，CMOS =互补金属氧化物半导体，HWP =半波片，L =透镜，LP =线性偏振器，MMF =多模光纤，OBJ =显微镜物镜， PBS =偏振分束器，SLM =空间光调制器（仅相） -仅适用于（A）的校准和（b）传输相关的横梁被描述请点击此处查看该图的放大版本。
Protocol
Representative Results
Discussion
实验设置（在协议步骤1）的组装需要的光学部件的相对于彼此的透彻对齐。最重要的方面是参考光束到SLM的，以确保高的PBR矩形发病率。
为了提高在设置两个以上的发射的信号，也可使用附加的分束器。作为替代，基于光纤的实施将更为紧凑和坚固允许系统是便携式的用于在生物光子学原位调查。如果单端的访问是可能只，基于模型的校准溶液20</…
Declarações
The authors have nothing to disclose.
Acknowledgements
The financial support by DFG (German research foundation, project CZ 55/30-1) for parts of this work is gratefully acknowledged.
Materials
| spatial light modulator | Holoeye | PLUTO‐VIS‐016 | |
| CMOS camera | Mikrotron | MC4082 | |
| diode‐pumped solid state laser | Laser Quantum | torus 532 | |
| CCD camera | IDS | U3‐3482LE‐M | CMOS camera; suitable as well |
| lens 1 | Qioptiq | G063204000 | |
| lens 2 | Qioptiq | G063203000 | |
| lens 3 | Thorlabs | AC508‐180‐A‐ML | |
| multimode fiber | Thorlabs | M14L02 | |
| beam splitters | Thorlabs | BS013 | 9x |
| polarizing beam splitters | Thorlabs | PBS251 | |
| mirrors | Thorlabs | PF10‐03‐P01 | 5x |
| microscope objectives | Thorlabs | RMS20X | 2x |
| half wave plates | Thorlabs | WPH10M‐532 | 2x |
| linear polarizer | Thorlabs | LPVISB050‐MP2 | |
| optical modulators | Thorlabs | MC2000B‐EC | 2x |
| linear and rotation stage for CMOS camera | Thorlabs | XYR1/M | |
| fiber connector | Thorlabs | S120‐SMA | 2x |
| reducing ring for microscope objectives | Qioptiq | G061621000 | 2x |
| xy adjustment for objective adapters | Qioptiq | G061025000 | 2x |
| z translation mount for fiber adapter | Thorlabs | SM1Z | 2x |
| rods for fiber alignment to objectives | Qioptiq | G061210000 | 8x |
| mounts for lenses 1 and 2 plus two phantom mounts | Qioptiq | G061047000 | 4x |
| rail carriers for objective and lens mounts | Qioptiq | G061372000 | 6x |
| rail for rail carriers | Qioptiq | G061359000 | 2x |
| adapter for CCD camera to 1 post | in-house | ||
| adapter for laser to 4 posts | in-house | ||
| mount for lens 3 | Thorlabs | LMR2/M | |
| mounts for half wave plates | Thorlabs | RSP1D/M | 2 |
| mounts for mirrors | Thorlabs | KM100 | 5x |
| mount for linear polarizer | Thorlabs | RSP05/M | |
| mounts for beam splitters and SLM | Thorlabs | KM100PM/M | 11x |
| clamping arms for beam splitters and SLM | Thorlabs | PM4/M | 11x |
| posts for mounts, rail carriers and adapters | Thorlabs | TR75/M | 29x |
| holders for posts | Thorlabs | PH50/M | 29x |
| pedestals for holders | Thorlabs | BE1/M | 29x |
| clamping forks for pedestals | Thorlabs | CF125 | 29x |
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