Design and experimental characterization of photonic crystal based optical modulators

Date

2023-6-23

Author

Akdeniz, Onur

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Photonic crystals are materials where the refractive index changes periodically. Thanks to the formation of photonic bands in specific crystal directions, they are helpful tools to control and manipulate light. The optical phase-shifter lengths can be significantly decreased by utilizing negative refraction phenomena in photonic crystal slabs to create large effective refractive index changes during band-to-band transitions. In this thesis, a silicon optical modulator utilizing negative refraction phenomena was analyzed for improvements in its design and experimentally characterized. The design uses the plasma dispersion effect to create optical carrier injection in one arm of a Mach Zehnder interferometer and achieve modulation. The analysis of the improvements in the design entailed explorations of the impacts of photonic crystal size and lattice structure. The photonic crystal region parameters were optimized to minimize the width of the photonic bandgap, effectively decreasing the optical losses and achieving the required phase changes in the on and off states of the modulator. Moreover, photonic bandgaps were examined through an optical spectrum analyzer, and the optical modulation operation was achieved during the experiments.

Subject Keywords

Optical communication systems, Mach Zehnder interferometer, Photonic crystals, Band to band transition, Plasma dispersion effect

URI

https://hdl.handle.net/11511/104474

Collections

Graduate School of Natural and Applied Sciences, Thesis