Fiber Optics for Fundamental Science and Applications

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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.