Fiber Optics for Fundamental Science and Applications

光纤是现代互联网的主干，与唯一的电信领域相比，它跨越的科学领域要大得多。增加光纤中的输入光功率通常会增加信号的传输距离，但是，过大的功率增加会产生非线性效应，这在电信中是可以避免的，因为它们会导致信号失真。克尔效应是一种非线性效应，它描述了光传输的有效折射率与功率的关系。通过自相位调制和交叉相位调制等技术，可以在空间和时间上控制非线性折射率。布里渊散射是另一种非线性效应，光纤波导的声模通过电致伸缩与光耦合。这一发现计划的总体愿景是研究光纤中的非线性光-物质相互作用，以促进基础科学和实际应用。目标1是研究与爱因斯坦广义相对论(GR)一致的偏振相关光在非线性光纤中传输的运动学。根据GR，光遵循零星等测地线的事实可以看出这种联系。在各向同性折射率为n的情况下，可以得到光在介质中的两个一级运动方程：d1/dt=±c/n。对于非线性折射率和偏振相关性，必须使用覆盖黎曼几何的芬斯勒几何。请注意，GR的基础是黎曼几何。使用更一般的芬斯勒几何学对偏振相关的非线性光运动学的基本理解可以在理解我们的宇宙方面产生新的想法，例如暗能量问题，因为芬斯勒几何学嵌入了时空扭曲和时空曲率等特征。GR的时空曲率已经给了我们一些概念，比如最近用Event Horizon Telescope展示的黑洞。目标2是建立基于前向和后向布里渊散射的分布式多参数(温度、应变和声阻抗)光纤传感模型。通过布里渊散射将声学模式与光耦合，使得光纤本身能够充当传感介质。目标3是发展用于分数轨道角动量纠缠光子对产生的薄金属楔形硫化物纤维。薄的金属楔形使分数轨道角动量模和硫化物核心的局部尖锐的金属曲率降低了非线性阈值光功率。这将提供一种与光纤兼容的量子纠缠光子对光源，有可能加快量子加密通信的应用。该研究项目将理论和应用相结合，将为加拿大科技行业和学术界培养一批高技能的研究生和本科生。

Optical fibers, the backbone of the modern internet, span a much larger area of scientific fields than the sole telecomm domain. Increasing the input light power in fibers normally increases the signal transmission distance, however, too large of a power increase will induce nonlinear effects, which are avoided in the telecomm since they lead to signal distortion. The Kerr effect is a nonlinear effect that describes the power dependence of the effective refractive index for light propagation. The nonlinear refractive index can be controlled both spatially and time varying, by techniques such as self-phase and cross-phase modulations. Brillouin scattering is another nonlinear effect, where acoustic modes of the fiber waveguide are coupled to the light via electrostrictions. The overarching vision of this discovery program is to study the nonlinear light-matter interactions in fibers for the purpose of advancing fundamental science and practical applications. Objective 1 is to study the Kinematics of polarization dependent light propagation in nonlinear fibers consistent with the Einstein's General Relativity (GR). This link is seen from the fact that according to GR, the light follows the geodesic of null magnitude. This can give rise to two first-order equations of motion for light in a medium with the case of isotropic refractive index n: dl/dt=±c/n. For the nonlinear refractive index and the polarization dependence one must use Finsler geometry that covers Riemannian geometry. Note that GR has its base in Riemannian geometry. The fundamental understanding of polarization dependent nonlinear light kinematics using more general Finsler geometry can generate new ideas in understanding of our universe such as issues of dark energy, because Finsler geometry embeds features like space-time torsion as well as space-time curvature. Space-time curvature in GR already gives us ideas like black-hole that is shown recently with Event Horizon Telescope. Objective 2 is to develop distributed multi-parameter (temperature, strain and acoustic impedance) model for fiber sensing based on the combined forward and backward Brillouin scatterings. Coupling of the acoustic modes with the light via Brillouin scattering enables the possibility of fiber itself acting as a sensing medium. Objective 3 is to develop thin metallic wedged chalcogenide fibers for the purpose of fractional orbital angular momentum entangled photon pair generation. The thin metallic wedge enables the fractional orbital angular momentum mode and local sharp metallic curvature at the chalcogenide core reduces the nonlinear threshold light power. This will supply a fiber-compatible quantum entangled photon pair source that has the potential to speed up the application of quantum encryption communication. Combining theory and application, this research program will train a cohort of highly-skilled graduate and undergraduate students for Canadian technological industries and academia.