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Tag Archive: optical sensing

  1. Tuneable Light Waves for Optical Sensing

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    OFS AcoustiSens® Optical Fibers used in random OPO system demonstration 

    By Regina Pynn, OFS Industrial Sensing & Networking Market Manager

    Once again, OFS optical fibers 是否在为研究人员将尖端技术从实验室带到实际应用中铺平道路. This time, we’re delving into the realm of optical fiber sensing 一种依赖于具有特定特征(如波长)的精心调谐光源的技术, power, and pulse width. 

    Generally optical fiber sensing starts with a laser, 但它们也有一个问题:激光的材料是经过精心挑选的，可以在特定的波长上发射稳定的光脉冲, limiting their flexibility. 波长调制系统有望在量子计算和其他领域带来令人兴奋的创新 LiDAR sensing.  

    opo可以利用AcoustiSens光纤中的故意散射来改变光脉冲的波长.
    OPOs can use the deliberate scattering in AcoustiSens optical fiber to change the wavelength of light pulses

    Enter the optical parametric oscillator (OPO). 它通过引导激光进入光学腔，将常规激光转换成可控波长的脉冲, bouncing it around nonlinear crystals and resonators. 当光穿过腔体并多次返回时，系统会改变波长并产生参数放大.  

    However, 这种令人眼花缭乱的表现有一个小问题:opo对温度和环境变化非常敏感. 即使很小的变化也会影响光的波长和功率，因为它离开了腔体, confining OPOs mostly to high-maintenance lab settings. 

    Researchers theorized that a random laser, which encourages scatter in the light source, 是否会使系统更加健壮，因为散射将来自激光的受控设计，而不受光学腔内环境变化的影响. 

    A groundbreaking paper from the University of Ottawa validates this concept. 一个团队首次展示了像OFS这样的增强传感光纤， AcoustiSens can make this idea a reality. AcoustiSens具有增强的瑞利散射，这种散射使OPO系统具有稳定性, tuned wavelengths in a simple and robust optical cavity. 

    祝贺渥太华大学的团队和所有致力于将opo从实验室中解放出来的技术人员. 

  2. Fiber Optic Network Cable Helps to Monitor Ridgecrest Aftershocks

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    Earthquake Ready?加州理工学院(Caltech)的地震学家正在使用 fiber optic network cable 监测和记录7月4日和5日加利福尼亚州里奇克莱斯特地震的余震. By using optical fiber, the scientists can gather, track, 更深入地分析每天数千次余震的数据.

    为了做到这一点，科学家们将一束光发送到一个未使用的或 “dark” fiber optic cable. When the light reaches tiny blemishes in the optical fiber, a small portion of the light is reflected back and recorded. 通过这种方式，每个光纤缺陷都充当了沿埋地光缆的可跟踪位置. 当地震波穿过地面时，电缆会略微膨胀和收缩. This change affects the travel time of light to and from the locations. 通过监测这些变化，地震学家可以监测地震波的运动.

    According to Caltech, 这种微小的光纤缺陷经常发生，以至于每隔几米的光纤就像一个单独的地震仪. In fact, 在三个不同的地点监测50公里的光纤电缆，大致相当于部署超过6公里的光纤电缆,000 seismometers in the area.

    加州理工学院在两次大地震发生后的几天内启动了这个项目，并开始联系一些团体，寻找距离足够近、距离足够长、可以使用的未使用的光纤电缆. 科学家们最终联系了加州宽带合作组织的数字395项目. The goal of the Digital 395 project is to build a new 583-mile fiber optic network 从北向南，沿着内华达山脉东部，经过里奇克莱斯特附近. Digital 395提供了三段光纤电缆，加州理工学院将传感仪器与之相连.

    从里奇克雷斯特光纤网络收集的信息将帮助地震学家更多地了解地震在地球上的传播方式, 特别是地震波是如何穿过里奇克莱斯特周围地区的.

  3. Optical Fiber “Senses” Change in Surroundings

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    Companies use optical fiber as a sensor to detect changes in temperature and pressure. 该技术通常用于监测桥梁和天然气管道等结构.

    现在，洛桑理工学院(EPFL)的研究人员发现了一种新的方法 optical fibers can identify when they are in contact with a liquid or a solid. 研究人员通过在光纤内的光束的帮助下产生声波来实现这一目标.

    A Sensor That Doesn’t Disrupt the Light

    Four factors affect the light carried by a glass optical fiber: intensity, phase, polarization and wavelength. 当某些东西拉伸纤维或温度变化时，这些因素会发生变化. These changes let the fiber act as a sensor by detecting cracks in structures or temperature changes. However, until now, 如果不让光线逃逸，用户就无法知道光纤周围到底发生了什么, which interrupts the light path.

    The method from EPFL uses a sound wave generated inside the fiber. This hyper-frequency wave regularly bounces off of the fiber’s walls. 这种回声在不同位置的变化取决于波接触的材料类型. 当光束离开光纤时，回声会在光线上留下印记，用户可以读取. 用户可以通过研究这种印记来检测和绘制纤维周围的环境, it is so faint that it barely disturbs the light within the fiber. In fact, 用户可以利用这项技术来感知光纤周围发生的事情，同时发送基于光的信息.

    In experiments, the researchers submerged their fibers in water and then in alcohol, and left them out in the open air. 每次，他们的系统都能正确地识别出纤维周围环境的变化. 该小组希望他们的技术在检测漏水方面有许多潜在的应用, as well as the density and salinity of fluids that touch the fiber.

    Spatial and Temporal Detection

    This method discerns changes in the surroundings with a time-based method. Each wave impulse is created with a slight time jag. Then, when the beam arrives, the delay is reflected. 研究人员可以看到任何干扰是什么，并确定它们的位置. The group can currently locate disturbances to within 10 meters, 但有了技术手段，并有望将精度提高到一米.

    To read and learn more, go HERE.