Designing periodic and aperiodic structures for nanophotinic devices.
Andonegui Artegui, Imanol
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Future all--optical networks will require to substitute the present electronic integrated circuitry by optical analogous devices that satisfy the compactness, throughput, latency and high transmission efficiency requirements in nanometer scale dimensions, outperforming the functionality of current networks. Thereby, existing dielectric materials do not confine light in a sufficiently small scale and so the physical size of these links and devices becomes unacceptable. In fact, if the optical chip does not exist in the liking of the electronic chip, photonic crystals have recently led to great hopes for a large-scale integration of optoelectronic components. Two-dimensional photonic crystals slabs obtained through periodic structuring of a planar optical waveguide, feature many characteristics which bring them closer to electronic micro-and nanostructures. This thesis explores non-trivial periodic and aperiodic dielectric nano-structures and to do so, we pose a photonic crystal design process guided by non-convex combinatory optimization techniques. In addition, this thesis proposes some novel coupling devices optimized to minimize insertion losses between silicon-on-insulator integrated waveguides and single mode optical fibers. Last but not least, this thesis explores periodic arrangements from a new perspective and reports on the first experimental evidence of topologically protected waveguiding in silicon. Furthermore, we propose and demonstrate that, in a system where topological and trivial defect modes coexist, we can probe them independently. Tuning the configuration of the interface, we observe the transition between a single topological defect and a compound trivial defect state.