Super Receivers for Visible Light Communications

在不久的将来，发光二极管（led）将取代所有其他光源——从照亮家庭和办公室的灯到汽车的前灯。除了提供照明外，这些led还可以用于传输数据，因此为创建新的无线数据传输基础设施提供了机会。智能手机、手表、平板电脑和其他设备对无线通信的需求正以每年50%的速度增长，需要新技术来增加传统WiFi的容量。在可见光通信中使用led提供了巨大的潜力来支持这种增长，并提供使用本地化无线通信的新服务。虽然led可以传输信息，但需要一个光学接收器来收集传输的光，将其转换为电信号并提取传输的数据。可传输的最大光量受到照明亮度和用户眼睛安全和舒适度的限制。因此，接收器的灵敏度最终决定了光数据可以传输的范围和/或最大可能的数据速率。现有的可见光通信接收器的灵敏度受限于收集光的方法和将光转换为电信号的设备的组合。在这个项目中，我们的目标是创造新的超级接收器，比现有的光学接收器更敏感；克服了传统的速度限制，灵敏度和易于校准；它们很薄，足够灵活，可以很容易地集成到任何设备上。将荧光聚光器和单光子雪崩光电二极管阵列这两种技术首次结合在一个接收器上，将实现性能上的巨大变化。第一种将使用荧光材料吸收透射光信号，并以不同的波长将其重新发射到探测器上。使用这种方法，我们将使用一个薄的、灵活的层来收集大面积的光，该层将发射的光引导并集中到其边缘。第二种技术是能够探测单个光子的光探测器。我们将开发在环境光存在的情况下计算发射器光子的方法。我们将探索如何优化荧光材料和光收集层，以有效地将光集中到一个或多个光探测器上，并开发通过优化数据表示方式来最大化数据传输量的方法。这些超级接收器将在自由空间可见光通信链路中进行测试，以量化其性能。我们的估计表明，这种方法可以使当前接收器的性能提高100倍，实现更快的数据传输，更长的传输范围，并能够在困难的环境中运行，例如在明亮的环境光下。

In the near future, light emitting diodes (LEDs) will replace all other sources of light - from the lamps that light homes and offices to the headlights of cars. As well as providing illumination, these LEDs can be used to transmit data, and so offer an opportunity to create a new wireless infrastructure for data transmission. The demand for wireless communications to smartphones, watches, tablets and other devices is growing at a rate of 50% per year, and new technologies are needed to augment the capacity of conventional WiFi. Using LEDs in visible light communications offers a huge potential capacity to support this growth and to provide new services that use localised wireless communications. While LEDs can transmit the information, an optical receiver is needed to collect the transmitted light, convert it to an electrical signal and extract the transmitted data. The maximum amount of light that can be transmitted is limited by the illumination brightness and concerns for the eye safety and comfort of users. The sensitivity of the receiver therefore ultimately determines the range over which optical data can be transmitted and/or the maximum possible data rate. The sensitivity of existing receivers for visible light communications is limited by a combination of the methods used to collect light and the devices used to convert this light to an electrical signal.In this project we aim to create new super receivers that are significantly more sensitive than existing optical receivers; that overcome conventional limits for combining speed, sensitivity and easy alignment; that are thin and flexible enough to be easily integrated onto any device. A dramatic change in performance will be achieved by combining two technologies- fluorescent concentrators and arrays of single-photon avalanche photodiodes- in a receiver for the first time. The first will use fluorescent materials to absorb the transmitted light signal and re-emit it at a different wavelength onto the detector. Using this method we will collect light over large areas using a thin, flexible layer which guides and concentrates the emitted light to its edges.The second technology is a light detector capable of detecting individual photons. We will develop methods to count photons from the transmitter in the presence of ambient light. We will explore how to optimise the fluorescent materials and light collecting layer to efficiently concentrate light onto one or more light detectors, and develop methods to maximise the amount of data transmitted by optimising how the data is represented. These super receivers will be tested in free-space visible light communications links to quantify their performance. Our estimates suggest that this approach could lead to a 100 times improvement in performance over current receivers, enabling faster data transmission, longer transmission ranges and the ability to operate in difficult environments, such as in the presence of bright ambient light.