用于通讯技术的高效有机光放大器的研究

Modern telecommunications are based around a worldwide back-bone of fibre-optic cables which encircle the globe carrying data at the speed of light. Despite phenomenally low losses experienced in these fibres it is still necessary to regularly amplify the optical signals every 70-100km. In addition to these attenuation losses, optical networks also suffer from losses at splices, connections and more dramatically optical components such as splitters. In order to overcome these losses optical amplification is required and this is traditionally performed using erbium doped fibre amplifiers (EDFAs). These rely on an intra-atomic transition in the erbium ion that emits at a wavelength of ~1.5 μm, the low loss window of silica fibres. The current global market for EDFAs is expected to grow from ~$900 million in 2012 to ~$2.8 billion by 2019 whereas the market for optical transceivers is expected to grow from $3.4 billion in 2012 to $5.1 billion in 2017..Due to the weak excitation properties of erbium ions, high powered lasersare necessary to achieve population inversion and thus optical gain.The laser is launched axially down erbium doped fibres of 10-30 m length, making these devices bulky and expensive. Various approaches such as integrating erbium doped glasses onto substrates like silicon to produce integrated technology andsensitising erbium have been tried but none of these have produced materials with the right collection of properties to be useful. We recently developed a new technology that allows us to fabricate waveguides onto silicon substrates and have demonstrated population inversion in the erbium ions whilst pumping using very low power (3mW) visible light. Initial modeling, suggests that we should be able to obtain optical gain in this material of at least 15 dB/cm. This approach not only replaces expensive lasers with cheap LEDs but also removes the need for axial pumping hence there is no need to integrate lasers accurately with the waveguide; a major technological problem with current approaches to silicon photonics. This technology allows us to fabricate optical amplifiers that can be directly integrated on to silicon facilitating a new approach to silicon photonics. Using our approach a device analogous to a 32 way optical splittercan be made that provides gain along itswhole length so that the losses inherent in existing optical splitters can be completely removed.

本项目针对目前基于掺铒激光器的光纤放大器较为笨重且价格贵、增益距离短等缺点，提出一种LEDs激发的新型硅基集成有机铒波导光放大器，试图发展一种低功率激发、高增益传输的新型有机光增益介质及相关器件制备技术。我们通过对铒离子与发色团之间能量传递的基本光物理过程，铒淬灭机制，系间穿越、新型敏化铒配合物反应机理的深入研究，探索制备具有良好光增益的有机铒材料；研究基于有机铒波导放大器的制备技术和加工工艺，制备出光增益大于20 dB且性能稳定的有机铒光放大器，并进行性能测试和表征，从而发展出一套与硅基光子学兼容的新型光学增益器件（或激光器）的制备理论及技术。本项目提供了一个可直接在硅基底上集成激光器的方法，其研究成果可为制造像零损耗分光器这样的新器件提供新的途径，也为集成光学的制造带来全新的技术，开辟一个新的重要科学、技术和商业发展机遇。

现代通信基于可使信息以光速在全球传播的纤维光缆。尽管光学信号在这些纤维中只有较低损耗，但光学信号每传播70-100km，仍需进行信号放大。传统上采用铒参杂纤维放大器（EDFAs）实现光放大。当前全球市场上EDFAs产值预计将从2012年的9亿美元增长到2019的28亿，且市场上光收发器产值预计将从2012年的34亿增长到2017年的51亿。EDFAs需单独高能泵浦激光器与10-30m长的纤维来实现粒子数反转和光增益。这将使器件体积庞大且昂贵。已试过多种方法来使铒参杂玻璃整合到基底上，但至今无人生产出正确属性集合的材料。我们最近研发了一种可克服以上问题并可在硅基上制造波导管的新技术。该原型器件表明可在该材料中实现至少15dB/cm的光增益。此法不仅利用便宜的LEDs替代了昂贵的激光器，且无需精确整合激光器和波导。我们可用此法制造可直接整合到硅基上的光放大器，这将促进硅光子学中新方法的发展。