Theoretical applied optics

光纤是通信的管道。学术界和工业界的研究人员正在研究所有限制接收端和传输端电光转换的光纤网络。然而，随着带宽和速度超过每波长信道10 GB/s的数据速率，许多现有的光纤网络无法在不遭受严重信号降级的情况下承载信息。限制因素包括光纤非线性、偏振模色散（PMD）、偏振相关损耗（PDL）和色散（CD）。光纤非线性描述了材料的偏振度随光的强度的变化，PMD是光传播速度的偏振依赖性。PDL是信号衰减的偏振依赖性，CD是传播速度的波长（颜色）依赖性。此外，这些物理效应相互作用，并且它们的值受到环境条件的影响，如温度、风在现场光纤中引起的应变。该方案为光纤通信网络开发了可靠的模拟、仿真和补偿工具。本课题研究的目的是为未来全光纤网络的发展提供参考。受激布里渊散射（SBS）是一种描述声子与光耦合的非线性效应，由于折射率的非线性变化，也会使信号传播变慢。布里渊慢光作为光自身调谐的光缓冲器，是实现传统通信光纤的关键技术之一，因此将在这一领域开展研究。光纤中的SBS效应也可以用作传感器，因为它的布里渊谱与局部温度和应变有关。由于光纤的柔韧性和微小的尺寸，基于SBS的光纤传感器得到了广泛的应用，例如，监测大型结构的安全性，火灾报警，石油和天然气管道故障报警等。拟议的传感研究是开发快速信号处理工具，以提高温度和应变测量的准确性。这种传感研究将对我们大型土木结构的安全产生巨大的实际影响（例如，最近在拉瓦尔魁北克的高速公路立交桥上发生的悲剧可以及早发现）。

Optical fibers are the pipeline of the telecommunication. Researchers in both academics and industries are investigating all optic fiber networks that limiting the electro-optic conversion at the receiver and transmission ends. However as the bandwidth and speed exceed the data rate of 10GB/s per wavelength channel many of the existing fiber networks are not able to carry the information without suffering severe signal degradation. The limiting factors include fiber nonlinearity, polarization mode dispersion (PMD), polarization dependent loss (PDL), and chromatic dispersion (CD). Fiber nonlinearity describes the material's polarizability change by light's intensity and PMD is the polarization dependence of the light propagation speed. PDL is the polarization dependence of the signal attenuation and CD is the wavelength (color) dependence of the propagation speed. Furthermore those physical effects interact and their values are affected by environmental conditions like temperature, wind induced strain in field fibers. This proposal develops reliable simulation, emulation and compensation tools for the fiber communication network. The objective of this communication research is to advance the future all optic fiber networks. One of the nonlinear effect, namely stimulated Brillouin scattering (SBS), describing the coupling of acoustic phonon with the light, could also slow the signal propagation due to the nonlinear change of refractive index. Researches will be conducted in this aera of Brillouin slow light in conventional communication fibers as it is one of the key enabling technology as an optical buffer tuned by light itself. SBS effect in fiber can also be employed as a sensor since its Brillouin spectra are related to local temperature and strain. Due to fiber's flexability and tiny size the SBS based fiber sensors find vast area of applications, e.g., monitoring safty of large structures, fire alarms, oil and gas pipeline failure warnings, etc. The proposed study on sensing is to develop fast signal processing tools to enhance the accuracy of the temperature and strain measurements. This sensing research will have enormous practical impacts to the safty of our large civil structures (e.g., recent tragedy at highway overpass in Laval Quebec could be detected early).