Name: transmission of multiple signals through an optical fiber using wavefront shaping
Uploaded: 2017-03-20T15:00:00.000+00:00
Duration: 9 min 43 s
Description: Watch this Scientific Journal Video about Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping at JoVE.com

The financial support by DFG (German research foundation, project CZ 55/30-1) for parts of this work is gratefully acknowledged.

1.组装实验装置<ol><li> 制备的基端侧 <ol><li>放置和固定在激光提供一个准直光束 - 或在光纤的出射面利用具有准直光学器件的光纤耦合激光。 </li><li>把偏振光束分离器（PBS），以将激光束分裂成参考和物体光束。通过在其旋转而旋转的HWP座，直到参考光束和物体光束（在远端侧）的功率大致相同转半波片（HWP）的方向。通过将屏幕分为两个参考和物光束进行检查。选择的PBS的取向，以使参考光束的偏振适合的偏振敏感空间光调制器（SLM）。 </li><li>把一个光束分离器（BS）到参考光束与参考光束分成两束。放置光调制器（OM），使得这两个光束从BS1来可以分别通过OM1和OM2，&lt;/ LI&gt; <li>结合两束传递OM1和OM2在BS2采用两个镜子。调节分束器和反射镜，使得两个光束在空间上分离。 </li><li>仔细对齐BS5，以确保两个光束的入射方向垂直于SLM的像素平面，忽略BS3和BS4在第一。首先，没有显示在SLM上， 也就是说 ，它的作用就像一个镜子直到校准（在整个步骤2）的端部。 </li><li>调整构成为了获得互补金属氧化物半导体（CMOS）相机在SLM平面的锐利图像的开普勒望远镜的位置和两个镜头（L）之间的距离。观看L1和L2的正确方向（平侧面彼此面对），以尽量减少像差。 </li></ol></li><li> 制备的远端侧 <ol><li>使用BS7到物体光束分成两束，并在使用两个反射镜BS8组合它们。再次，调整光束分离器和英里rrors使两个光束在空间上分离。 </li><li>使用BS9它们旨在显微镜物镜（OBJ）偏转两个光束。集中OBJ2的多模光纤（MMF）的前端。通过观察从使用L3和电荷耦合器件（CCD）照相机该MMF背反射检查对焦。 </li></ol></li><li> 连接的近端和远端侧 <ol><li>照准从物光束退出MMF采用OBJ1的光。 </li><li>拆分使用BS6物体光束，首先忽略线性偏振器（LP）。与BS3两个参考光束和BS4采用镜面结合两种对象横梁。调节分束器和反射镜，使得每一对基准和物体光束重叠在SLM，用小角度（小于1度）相交。 </li><li>确保参考的功率和物体光束是通过转动的HWP的方向，根据步骤1.1.2大致相等。 </li><li>检查干扰pattern（离轴全息图）的CMOS摄像头，并相应地调整交叉角。增加角度，直到干涉条纹间距大致等于CMOS摄像头上的两个像素的大小。 </li><li>调整LP的取向物体光束和参考光束的偏振相匹配，以获得在CMOS摄像机图像中的干涉图案的最大对比度，使相机图像显示鲜明条纹。 </li></ol></li></ol> 2.校准系统<ol><li> 校准SLM和CMOS的像素关系 <ol><li>照亮只使用参考光束中的一个的整个SLM并阻断其它参考和对象束。 </li><li>捕获与CMOS照相机SLM的图像。 </li><li>得到SLM的CMOS摄像图像中的使用绘图软件，并在PC上的鼠标光标的左上角， 例如的坐标。使用这些像素坐标原点对于SLM。 </li><li>删除所有光束块。 </li></ol></li><li> 校准信号路径 <ol><li>同时阻断参考光束2和物体光束2。 </li><li>捕获与CMOS照相机全息图的图像。评估采用了棱角分明谱法19记录的全息图的阶段。计算的倒相在梁1的相应区域。 </li><li>卸下前束块，现在都阻挡参考光束1和对象梁1。 </li><li>捕获与CMOS照相机全息图的图像。测量在再次使用角谱方法记录的全息图的相位。计算的倒相在光束2的相应区域。 </li><li>删除所有光束块。 </li></ol></li></ol> 3.传递信号<ol><li>块的对象光束。 </li><li>在梁1和2的相应区域缝合所计算的反转相位图像一起并显示在SLM上整个图像，通常使用的计算机图形端口。 </li><li>通过激活OM1和OM2启动输入信号1和2的调制。 </li><li>观察输出信号1和2中的CCD照相机上。 </li></ol>

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The authors have nothing to disclose.

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需要完成作为未来步骤。越信号被发送，所述多个模式将被要求在SLM和CMOS相机双方所以更多的像素将不得不介入用于实现PBR。此外，像素的数目应大于或等于模式的数量。在广告中下，两个SLM的像素大小应该是最小的斑点直径在近端侧的大小的两倍。据进一步建议，SLM至少有四个位的位深度。采用CMOS表示相机的像素数超过该SLM的像素的数量。然而，代替的CMOS摄像任何其他检测器类型都可以使用， 例如 CCD。这同样适用于采用CCD表示的摄像机。 所提出的方法的一个限制是该光源需要大的相干长度（低光谱带宽），以保证在所需要的相位测量的全息图的干扰。此外，该系统必须是稳定的， 即没有纤维或校准和变速器之间的光学设置的变化是可容许的，比校准，这是目前低于1秒的持续时间更快。为长纤维和高信号频率，不同的纤维模的群速度色散具有要考虑的，并且可以降低该信号。以补偿，可以使用梯度折射率光纤或时空扭曲21的校正。 相较于以前的相位共轭的方法，我们提出的SDM方法可以在应用中，独立的光信号必须传送中使用。相位共轭方法是关于时间的性能优势，相比迭代方法或完整矩阵的决心。 一名潜在的应用领域可能是内镜下光传输，例如在光陷阱或在光遗传学。对于光遗传学，我们的方法对于单个神经元，以便分析脑的行为和更好地了解神经变性疾病的选择性照明是有利的。

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）。 <img alt="图1" src="/files/ftp_upload/55407/55407fig1.jpg" /> 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<a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55407/55407fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

<table><tbody><tr><td>spatial light modulator</td><td>Holoeye</td><td>PLUTO-VIS-016</td><td></td></tr><tr><td>CMOS camera</td><td>Mikrotron</td><td>MC4082</td><td></td></tr><tr><td>diode-pumped solid state laser</td><td>Laser Quantum</td><td>torus 532</td><td></td></tr><tr><td>CCD camera</td><td>IDS</td><td>U3-3482LE-M CMOS</td><td>camera; suitable as well</td></tr><tr><td>lens 1</td><td>Qioptiq</td><td>G063204000</td><td></td></tr><tr><td>lens 2</td><td>Qioptiq</td><td>G063203000</td><td></td></tr><tr><td>lens 3</td><td>Thorlabs</td><td>AC508-180-A-ML</td><td></td></tr><tr><td>multimode fiber</td><td>Thorlabs</td><td>M14L02</td><td></td></tr><tr><td>beam splitters</td><td>Thorlabs</td><td>BS013</td><td>9x</td></tr><tr><td>polarizing beam splitters</td><td>Thorlabs</td><td>PBS251</td><td></td></tr><tr><td>mirrors</td><td>Thorlabs</td><td>PF10-03-P01</td><td>5x</td></tr><tr><td>microscope objectives</td><td>Thorlabs</td><td>RMS20X</td><td>2x</td></tr><tr><td>half wave plates</td><td>Thorlabs</td><td>WPH10M-532</td><td>2x</td></tr><tr><td>linear polarizer</td><td>Thorlabs</td><td>LPVISB050-MP2</td><td></td></tr><tr><td>optical modulators</td><td>Thorlabs</td><td>MC2000B-EC</td><td>2x</td></tr><tr><td>linear and rotation stage for CMOS camera</td><td>Thorlabs</td><td>XYR1/M</td><td></td></tr><tr><td>fiber connector</td><td>Thorlabs</td><td>S120-SMA</td><td>2x</td></tr><tr><td>reducing ring for microscope objectives</td><td>Qioptiq</td><td>G061621000</td><td>2x</td></tr><tr><td>xy adjustment for objective adapters</td><td>Qioptiq</td><td>G061025000</td><td>2x</td></tr><tr><td>z translation mount for fiber adapter</td><td>Thorlabs</td><td>SM1Z</td><td>2x</td></tr><tr><td>rods for fiber alignment to objectives</td><td>Qioptiq</td><td>G061210000</td><td>8x</td></tr><tr><td>mounts for lenses 1 and 2 plus two phantom mounts</td><td>Qioptiq</td><td>G061047000</td><td>4x</td></tr><tr><td>rail carriers for objective and lens mounts</td><td>Qioptiq</td><td>G061372000</td><td>6x</td></tr><tr><td>rail for rail carriers</td><td>Qioptiq</td><td>G061359000</td><td>2x</td></tr><tr><td>adapter for CCD camera to 1 post</td><td></td><td></td><td>in-house</td></tr><tr><td>adapter for laser to 4 posts</td><td></td><td></td><td>in-house</td></tr><tr><td>mount for lens 3</td><td>Thorlabs</td><td>LMR2/M</td><td></td></tr><tr><td>mounts for half wave plates</td><td>Thorlabs</td><td>RSP1D/M</td><td>2</td></tr><tr><td>mounts for mirrors</td><td>Thorlabs</td><td>KM100</td><td>5x</td></tr><tr><td>mount for linear polarizer</td><td>Thorlabs</td><td>RSP05/M</td><td></td></tr><tr><td>mounts for beam splitters and SLM</td><td>Thorlabs</td><td>KM100PM/M</td><td>11x</td></tr><tr><td>clamping arms for beam splitters and SLM</td><td>Thorlabs</td><td>PM4/M</td><td>11x</td></tr><tr><td>posts for mounts, rail carriers and adapters</td><td>Thorlabs</td><td>TR75/M</td><td>29x</td></tr><tr><td>holders for posts</td><td>Thorlabs</td><td>PH50/M</td><td>29x</td></tr><tr><td>pedestals for holders</td><td>Thorlabs</td><td>BE1/M</td><td>29x</td></tr><tr><td>clamping forks for pedestals</td><td>Thorlabs</td><td>CF125</td><td>29x</td></tr></tbody></table>

transmission of multiple signals through an optical fiber using wavefront shaping

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。

<html>在2米长的光纤的前端侧的典型输出信号在图2中被描绘。需要注意的是所希望的焦斑（峰值）是伴随着不期望的斑点图案（背景），这是由于DOPC的缺陷作为一个原则问题。相应峰 - 背景比（PBR）等于53（仅信号1是"开"），36分别（只信号2"上"）和20（两个信号1和2"上"）这里， 。用于:（1710目前）时，它支持的模式的较大数量的纤维将PBR可以增加。 由于有限的PBR，输出信号之间的串扰的结果，这是在图3中显示。与频率f1和f2的量至-24 dB到周期信号之间的串扰（从信号2到信号1）和-29分贝（从信号1到信号2）。 ntent"FO:保together.within页="1"&gt; <img alt="图2" src="/files/ftp_upload/55407/55407fig2.jpg" /> 图2:远端光纤端的图像，输出信号1（左），信号2（中心）和两个信号1和信号2（右）的传输。强度[金] <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55407/55407fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/55407/55407fig3.jpg" /> 图3:所发送的输出信号1（左）和2（右）的时空频谱。振幅[金] <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55407/55407fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping at JoVE.com

Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

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.

通过光纤使用波前整形多个信号的传输

The transmission of multiple independent optical signals through a multimode fiber is accomplished using wavefront shaping in order to compensate for the ...

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9.8K 次观看.  TU Dresden. 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.

视频: Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

Quasi-light Storage for Optical Data Packets

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing of the signals is done in the electrical domain. Direct storage in the optical domain would avoid the transfer of the packets to the electrical and back to the optical domain in every network node and, therefore, increase the speed and possibly reduce the energy consumption of telecommunications. However, light consists of photons which propagate with the speed of light in vacuum. Thus, the storage of light is a big challenge. There exist some methods to slow down the speed of the light, or to store it in excitations of a medium. However, these methods cannot be used for the storage of optical data packets used in telecommunications networks. Here we show how the time-frequency-coherence, which holds for every signal and therefore for optical packets as well, can be exploited to build an optical memory. We will review the background and show in detail and through examples, how a frequency comb can be used for the copying of an optical packet which enters the memory. One of these time domain copies is then extracted from the memory by a time domain switch. We will show this method for intensity as well as for phase modulated signals.

The article describes a procedure to store optical data packets with an arbitrary modulation, wavelength, and data rate. These packets are the basis of modern telecommunications.

准光存储光学数据包

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing ...

科研

工程学

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

无序横向安德森本地化光聚合物光纤的制备和表征

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

写布拉格光栅在多核纤维

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

Generation and Coherent Control of Pulsed Quantum Frequency Combs

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional states on-chip in a practical way have remained elusive due to the increasing complexity of the quantum circuitry needed to prepare and process such states. Here, we outline how high-dimensional, frequency-bin entangled, two-photon states can be generated at a stable, high generation rate by using a nested-cavity, actively mode-locked excitation of a nonlinear micro-cavity. This technique is used to produce pulsed quantum frequency combs. Moreover, we present how the quantum states can be coherently manipulated using standard telecommunications components such as programmable filters and electro-optic modulators. In particular, we show in detail how to accomplish state characterization measurements such as density matrix reconstruction, coincidence detection, and single photon spectrum determination. The presented methods form an accessible, reconfigurable, and scalable foundation for complex high-dimensional state preparation and manipulation protocols in the frequency domain.

A protocol is presented for the practical generation and coherent manipulation of high-dimensional frequency-bin entangled photon states using integrated micro-cavities and standard telecommunications components, respectively.

脉冲量子频率梳的产生与相干控制

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional ...

High-Throughput Total Internal Reflection Fluorescence and Direct Stochastic Optical Reconstruction Microscopy Using a Photonic Chip

Total internal reflection fluorescence (TIRF) is commonly used in single molecule localization based super-resolution microscopy as it gives enhanced contrast due to optical sectioning. The conventional approach is to use high numerical aperture microscope TIRF objectives for both excitation and collection, severely limiting the field of view and throughput. We present a novel approach to generating TIRF excitation for imaging with optical waveguides, called chip-based nanoscopy. The aim of this protocol is to demonstrate how chip-based imaging is performed in an already built setup. The main advantage of chip-based nanoscopy is that the excitation and collection pathways are decoupled. Imaging can then be done with a low magnification lens, resulting in large field of view TIRF images, at the price of a small reduction in resolution. Liver sinusoidal endothelial cells (LSECs) were imaged using direct stochastic optical reconstruction microscopy (dSTORM), showing a resolution comparable to traditional super-resolution microscopes. In addition, we demonstrate the high-throughput capabilities by imaging a 500 &#181;m x 500 &#181;m region with a low magnification lens, providing a resolution of 76 nm. Through its compact character, chip-based imaging can be retrofitted into most common microscopes and can be combined with other on-chip optical techniques, such as on-chip sensing, spectroscopy, optical trapping, etc. The technique is thus ideally suited for high throughput 2D super-resolution imaging, but also offers great opportunities for multi-modal analysis.

Chip-based super-resolution optical microscopy is a novel approach to fluorescence microscopy and offers advantages in cost effectiveness and throughput. Here, the protocols for chip preparation and imaging are shown for TIRF microscopy and localization-based super-resolution microscopy.

使用光子芯片的高通量总内反射荧光和直接随机光学重建显微镜

Total internal reflection fluorescence (TIRF) is commonly used in single molecule localization based super-resolution microscopy as it gives enhanced ...

生物化学

Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator

The aim of this article is to visually demonstrate the utilization of an interferometric method for encoding complex fields associated with coherent laser radiation. The method is based on the coherent sum of two uniform waves, previously encoded into a phase-only spatial light modulator (SLM) by spatial multiplexing of their phases. Here, the interference process is carried out by spatial filtering of light frequencies at the Fourier plane of certain imaging system. The correct implementation of this method allows arbitrary phase and amplitude information to be retrieved at the output of the optical system.
It is an on-axis, rather than off-axis encoding technique, with a direct processing algorithm (not an iterative loop), and free from coherent noise (speckle). The complex field can be exactly retrieved at the output of the optical system, except for some loss of resolution due to the frequency filtering process. The main limitation of the method might come from the inability to operate at frequency rates higher than the refresh rate of the SLM. Applications include, but are not limited to, linear and non-linear microscopy, beam shaping, or laser micro-processing of material surfaces.

We show how to encode the complex field of laser beams by using a single phase element. A common-path interferometer is employed to mix the phase information displayed into a phase-only spatial light modulator to finally retrieve the desired complex field pattern at the output of an optical imaging system.

利用相位空间光调制器建立激光光束的振幅和相位

The aim of this article is to visually demonstrate the utilization of an interferometric method for encoding complex fields associated with coherent laser ...

Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped fiber laser is built completely using commercially available parts, including $8,000 in fiber optic and pump laser components, plus $4,800 in standard optical components and extra-cavity accessories. Researchers new to fiber optic device fabrication may also consider investing in basic fiber splicing and laser pulse characterization equipment (~$63,000). Important for optimal laser operation, methods to verify true versus apparent (partial or noise-like) mode-locked performance are presented. This system achieves 70 fs pulse duration with a center wavelength of approximately 1,070 nm and a pulse repetition rate of 31 MHz. This fiber laser exhibits the peak performance that may be obtained for an easily assembled fiber laser system, which makes this design ideal for research laboratories aiming to develop compact and portable fs laser technologies that enable new implementations of clinical multiphoton microscopy and fs surgery.

A method is presented to build a custom low-cost, mode-locked femtosecond fiber laser for potential applications in multiphoton microscopy, endoscopy, and photomedicine. This laser is built using commercially available parts and basic splicing techniques.

用于多光子显微镜的全正常分散飞秒光纤激光器的低成本定制制造和模式锁定操作

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped ...

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for moving mechanical parts. This technology is particularly useful for beam steering applications. Here, we focus on OPAs integrated into SiN photonic circuits for a wavelength in the near infrared. A characterization method of such circuits is presented, which allows the output beam of integrated OPAs to be shaped and steered. Furthermore, using a wafer-scale characterization setup, several devices can easily be tested across multiple dies on a wafer. In this way, fabrication variations can be studied, and high-performance devices identified. Typical images of OPA beams are shown, including beams emitted from OPAs with and without a uniform waveguide length, and with varying numbers of channels. In addition, the evolution of output beams during the phase optimization process and beam steering in two dimensions is presented. Finally, a study of the variation in the beam divergence of identical devices is performed with respect to their position on the wafer.

Here, we describe the operation of a SiN integrated photonic circuit containing optical phased arrays. The circuits are used to emit low divergence laser beams in the near infrared and steer them in two dimensions.

晶圆级试验站上SiN集成光学相控阵列的特性

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

使用多色荧光检测液滴微流控光纤

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

生物工程

Optimizing Brillouin Optical Time-Domain Analyzers Based on Gain Spectrum Engineering

Demonstrated is a unique method for sensing performance enhancement in Brillouin optical time-domain analyzers (BOTDA). A Brillouin gain spectrum (BGS) is superimposed with two symmetric Brillouin loss spectra (BLS). This leads to a complex engineered spectrum shape that is more resistant to the sensing system noise. Instead of only one pump and probe interaction as in the conventional BOTDA setup, three optical probe waves are exploited, with one probe located in the BGS and the other two symmetrically in the BLS. Due to the resistance and insensitivity of the engineered spectrum shape to the noise, the sensing performance is enhanced by 60% and the measurand resolution is doubled.

A protocol for Brillouin optical time-domain analyzers based on gain spectrum engineering is presented. Enhancements in the sensing performance, including sensing range and measurand resolution are achieved and the excess Brillouin intensity noise is studied. The protocol introduces a new way to enhance distributed Brillouin sensing performance.

Demonstrated is a unique method for sensing performance enhancement in Brillouin optical time-domain analyzers (BOTDA). A Brillouin gain spectrum (BGS) is ...