Investigation of optical and electro-optical effects at material interfaces

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PhD; 2023; Physics

The key questions addressed in this thesis are related to light-matter interactions at the material interfaces and are related to both plasmonic as well as Pockels effects. Plasmonics enables the design of compact photonic circuits with sub-micron electric field confinements and authorizes optical signal processing at the nanoscale. At the same time, the Pockels effect is necessary for designing on-chip interferometers and ultra-high-speed modulators. These two are crucial for integrated optics and photonics engineering. Integrated optics deals with miniaturizing large-scale optical signal processing circuit functionalities on a small footprint. This leads to performance enhancement as well as low power consumption. An electro-optic modulator is one of the most integral parts of an integrated photonic circuit. LiNbO3 is a well-known material with asymmetric crystal symmetry with a high Pockels coefficient of around 40 pm/V. However, integrating asymmetric crystals on a chip leads to slow and expensive fabrication processes. Instead, considering amorphous and poly-crystalline materials, their fabrication procedure is cost-effective and can be deposited rapidly using solution-processed techniques. In the first part of this thesis, we present an observation of the Pockels effect at the interface of a sol-gel spin-coated amorphous titanium dioxide and a poly-crystalline metal.