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研究人员希望利用未使用的网络, 暗光纤电缆 to help detect underground sound waves that can warn of an impending earthquake.
数百万英里未使用的， 暗光纤电缆 都安装在地下. A research team of scientists from the University of 加州 (Berkeley) 和 Lawrence Berkeley National Lab have been experimenting with a new predictive technique. This method may gather measurements of movement in the Earth’s crust that are superior to those obtained by current seismic detection systems.
测量活动
In 地震学, scientists often have only a small number of sensors to use in detecting earthquakes. 这就是为什么测量地球表面的振动是不均匀的, “危险的”风险. 也, 一些地震活跃地区手头有许多传感器, 而远离移动板块的地方可能很少. This variation in equipment can make it tough to measure seismic vibrations in places where, 例如, 水力压裂引发地震. 使用新方法, 用户可以把每根几英尺长的光纤电缆变成一个独立的 地震传感器.
In this new experiment, the research team “borrowed” from other groups who have developed 分布式声传感 (达斯)方法. 在达斯中，激光脉冲用于检测沿光纤/电缆的微小振动. 研究人员沿着光学装置插入称为询问器的装置 纤维/电缆. 这些询问装置发出并感应短红外激光脉冲. 由地震活动触发, tiny strains on the optical 纤维s cause some of the laser light to be reflected 和 then bounced back to the sensor. By sending rapid pulses, the scientists can detect changes in the light scattering over time. 通过了解光速，他们可以确定活动发生的位置.
“真实世界”测试
With this latest technique, the researchers essentially tested the 达斯 method in the real world. 他们把审讯者的电源接通 光缆 沿着能源部暗纤维试验台的线路. 绵延13000英里的 电信光纤 在美国西部.S. 用于测试新的通信设备. 研究人员的目标是西萨克拉门托附近的一段17英里长的电缆, 加州, 并记录了7月28日的数据, 2017, 到1月18日, 2018.
The research team successfully recorded information on the speed of sound waves traveling through the Earth. 事实上，在2017年9月，他们发现并测量了巨大的8.墨西哥发生1级地震(一个世纪以来袭击墨西哥的最强地震).
2013年，美国间谍爱德华·斯诺登(Edward Snowden)被捕.S. 国家安全局承包商, leaked documents showing that intelligence agencies were spying on the data of private citizens. 一个令人不安的事实是间谍窃听到了 光纤电缆 获取通过这些电缆传输的大量数据.
Snowden’s disclosures pushed researchers to use quantum science to make this type of hacking impossible. 最后，有进展的报告.
量子密钥分发方法
一家名为Quantum exchange的初创公司将接入500英里的 光缆 沿着U东部.S. 海岸. Quantum will use this cable to create the country’s first quantum key distribution (QKD) network.
Quantum Xchange’s “QKD approach” would send an encoded message in bits while transmitting the decoding keys as quantum bits, 或量子位元. 量子比特通常以光子的形式，很容易沿着光纤电缆传输. 然而, 任何监视量子比特的企图都会立即破坏其脆弱的量子态, 删除所有数据，留下入侵痕迹.
One possible issue is that “trusted nodes” must be used to send quantum keys over long distances. 这些节点充当中继器，在典型的网络中增强信号 数据电缆. Quantum exchange计划在其整个网络中拥有13个可信节点. 在这些节点上，密钥首先被转换成比特. 然后，它们被变回量子态，继续发送. In other words, a hacker could theoretically steal these bits as they are momentarily vulnerable.
另一种方法是量子隐形传态
伴随着这则新闻, 芝加哥大学, the Fermi National Accelerator Laboratory 和 Argonne National Laboratory will jointly develop a test bed to use quantum teleportation to create secure 数据传输.
量子隐形传态将利用纠缠来消除被黑客入侵的风险. 纠缠在单个量子态中产生一对量子比特(通常是光子). A change in one photon instantly affects the linked photon, even if they are far apart. 因此，从理论上讲，它应该是不可能被破解的 数据传输 使用纠缠. 这是因为篡改其中一个量子比特会破坏两个量子态.
Dr. Awschalom领导了这个涉及大学和国家实验室的项目. The goal is to have the test bed use a “plug-和-play” approach that will let the researchers experiment 和 evaluate different techniques for entangling 和 transmitting qubits.
加州理工学院的工程师们创造了世界上最小的机器人 光纤陀螺仪帮助导航. Five hundred times smaller than a regular gyroscope, this new gyro can fit on a grain of rice. This research breakthrough could lead to more accurate 纤维 optic gyros compared to mechanical units.
光纤陀螺仪使用光纤传感器检测位置或方向的变化 萨尼亚克效应. 这样，光学陀螺仪的功能与机械陀螺仪相似. 然而, the optical gyro operates by using light passing through a coil of optical 纤维.
Inside a typical optical gyroscope, a spooled-up optical 纤维 carries pulses of laser light. 有些脉冲是顺时针运动，有些是逆时针运动. The gyro measures rotation by detecting tiny changes in how these pulses arrive at a sensor. 研究人员试图制造更小的光学陀螺仪. 然而, 随着陀螺仪尺寸的缩小, the signals from its sensor have grown weaker until they are drowned out by “noise” from scattered light.
Optical gyroscopes that use the 萨尼亚克效应 to measure rotation could eventually be miniaturized onto nano-photonic platforms. 然而, 热波动, component drift 和 fabrication mismatch often limit the signal-to-noise ratio of these gyros. 因为微型装置的信号会更弱, 研究人员还没有制造出集成的纳米光子光纤陀螺仪.
对光纤传感感兴趣? 如果是这样的话, you’ll want to check out the “来自前线的故事 of 光纤传感” webinar presented by OptaSense 和 sponsored by the 光纤传感 Association (FOSA).
Whether it’s detecting pipeline leaks, damage to railroads or intrusion at critical facilities, 光纤传感 plays an increasingly important role in protecting 和 keeping key infrastructure assets operating globally.
The webinar features 光纤传感 installations across a wide range of industry verticals, 申请及地点, including system action videos with the challenges 和 successes of actual deployments.
支持全球数据流量的指数级增长, 100gb /s海底传输系统正在跨洋链路上安装. These systems offer capacity up to ~10 Tb/s on a single core 纤维 using a C-b和 Erbium doped 纤维 amplifier (EDFA).
然而, there are distinct challenges involved in developing 和 deploying high-capacity transoceanic distance transmissions systems. One issue is the need to improve optical signal-to-noise ratio (OSNR) within the entire C- 和 L-b和s. Another limitation lies in delivering electrical power to the offshore equipment supplying EDFA pumps. 除了, long haul undersea submarine systems are typically much longer than terrestrial systems 和 have unique requirements for 光缆s 和 repeaters used in harsh subsea environments.
在SubOptic 2016上发表的一份新白皮书中, OFS 和 OFS实验室 researchers discuss key 纤维 和 amplifier technologies that help users to achieve high capacity 和 long reach for submarine transmission systems. 这些技术包括超大有效面积, 低损耗光纤及其对性能的影响, along with key amplification techniques for both repeatered 和 repeaterless submarine systems.
研究人员希望利用未使用的网络, 暗光纤电缆 to help detect underground sound waves that can warn of an impending earthquake.
加州理工学院的工程师们创造了世界上最小的机器人 
