Zhang Xi, Feng Zitong, Marpaung David, Fokoua Eric Numkam, Sakr Hesham, Hayes John Richard, Poletti Francesco, Richardson David John, Slavík Radan
Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK.
Laser Physics and Nonlinear Optics Group, Faculty of Science and Technology, MESA + Institute for Nanotechnology, University of Twente, Enschede, 7500 AE, The Netherlands.
Light Sci Appl. 2022 Jul 7;11(1):213. doi: 10.1038/s41377-022-00908-3.
There are a host of applications in communications, sensing, and science, in which analogue signal transmission is preferred over today's dominant digital transmission. In some of these applications, the advantage is in lower cost, while in others, it lies in superior performance. However, especially for longer analogue photonics links (up to 10 s of km), the performance is strongly limited by the impairments arising from using standard single-mode fibres (SSMF). Firstly, the three key metrics of analogue links (loss, noise figure, and dynamic range) tend to improve with received power, but this is limited by stimulated Brillouin scattering in SSMF. Further degradation is due to the chromatic dispersion of SSMF, which induces radio-frequency (RF) signal fading, increases even-order distortions, and causes phase-to-intensity-noise conversion. Further distortions still, are caused by the Kerr nonlinearity of SSMF. We propose to address all of these shortcomings by replacing SSMFs with hollow-core optical fibres, which have simultaneously six times lower chromatic dispersion and several orders of magnitude lower nonlinearity (Brillouin, Kerr). We demonstrate the advantages in this application using a 7.7 km long hollow-core fibre sample, significantly surpassing the performance of an SSMF link in virtually every metric, including 15 dB higher link gain and 6 dB lower noise figure.
在通信、传感和科学领域有许多应用，其中模拟信号传输比当今占主导地位的数字传输更受青睐。在其中一些应用中，优势在于成本更低，而在其他应用中，则在于性能更优。然而，特别是对于较长的模拟光子链路（长达数十公里），性能受到使用标准单模光纤（SSMF）所产生的损伤的严重限制。首先，模拟链路的三个关键指标（损耗、噪声系数和动态范围）往往会随着接收功率的增加而改善，但这受到SSMF中受激布里渊散射的限制。进一步的性能下降是由于SSMF的色散，它会导致射频（RF）信号衰落、增加偶数阶失真并引起相位到强度的噪声转换。此外，SSMF的克尔非线性还会导致更多的失真。我们建议用空心光纤取代SSMF来解决所有这些缺点，空心光纤的色散同时低六倍，非线性（布里渊、克尔）低几个数量级。我们使用一个7.7公里长的空心光纤样本展示了在该应用中的优势，在几乎每个指标上都显著超过了SSMF链路的性能，包括链路增益高15dB和噪声系数低6dB。
