Multimode waveguides on lithium niobate-on-insulator (LNOI) and silicon-on-insulator (SOI) platforms are numerically investigated in buried, rib, and strip configurations. Performance of waveguides is compared in terms of waveguide cross-sectional area, dispersion, mode hybridization, and power confinement for both quasi-transverse electric and quasi-transverse magnetic modes. Tall waveguides with single mode in the horizontal direction, supporting higher order modes in the vertical direction, are analyzed. Also, wide waveguides with single mode in the vertical direction, supporting higher order modes in the horizontal direction, are studied. Designs that overcome mode hybridization are proposed, which are well suited for applications such as optical interconnects. LNOI waveguides were found to exhibit lower dispersion in all the configurations, with power confinement and physical dimensions comparable to those of SOI waveguides. The results are instrumental in design optimization of multimode components for on-chip mode-division multiplexing schemes and multiparameter sensing applications. Electro-optic effect is also illustrated in a buried multimode LNOI waveguide that is largely useful in modulation and switching applications.
Parametric comparison of ultra-compact few-mode waveguides of three types (strip, rib, and buried) on thin-film Lithium Niobate On Insulator (LNOI) and SOI platforms is presented. Performance of waveguides is compared in terms of waveguide cross-sectional area, mode loss, dispersion, mode-hybridization and power confinement for both quasitransverse electric (qTE) and quasi-transverse magnetic (qTM) modes. It is found that LNOI waveguides exhibit lower dispersion with physical dimensions comparable to that of SOI waveguides. The results are vital in choosing an optimum configuration of few-mode waveguides which is crucial for designing few-mode devices in mode-multiplexing schemes.
Quantum communication or more specifically quantum information processing is considered as the future of information science and technology. In this paper we propose a scheme to implement quantum communication at the device level using integrated optics. We implement the quantum communication protocol BB84, in a waveguide based circuit using integrated optics. We also propose a high dimensional quantum key distribution method implementation using integrated optics. In the earlier one polarized photons are used as the carriers of quantum information, while in second one electromagnetic modes in the waveguide are used to carry quantum information. The high dimensional quantum communication method is used to increase the information content of protocol thus increasing on the data rates. This is done by encoding into a larger state space. We have used electromagnetic modes for encoding since the polarization method is not efficient to carry information in a larger state space.