Spatially varying polarization of guided fundamental mode in a titanium indiffused periodically poled lithium niobate waveguide

Abstract The spatially varying polarization behavior of an optical guided mode in a Ti-indiffused lithium niobate (Ti:LiNbO $$_3$$ ) waveguide is investigated. Ti indiffusion causes different rates of increase for the ordinary ( $$n_o$$ ) and extraordinary ( $$n_e$$ ) refractive indices in the waveg...

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Bibliographic Details
Main Authors: Nasrin Moeini, Rahman Nouroozi
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-08007-0
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Summary:Abstract The spatially varying polarization behavior of an optical guided mode in a Ti-indiffused lithium niobate (Ti:LiNbO $$_3$$ ) waveguide is investigated. Ti indiffusion causes different rates of increase for the ordinary ( $$n_o$$ ) and extraordinary ( $$n_e$$ ) refractive indices in the waveguide, creating a distinct birefringence ( $$n_o \ne n_e$$ ). The calculated results indicate the formation of C-points and L-lines in the generated spatially varying polarization guided modes (SVPGMs) at specific propagation lengths. Since controlling and tuning SVPGMs via propagation alone is challenging, electro-optical control and tuning of the generated SVPGMs in a Ti-indiffused periodically poled lithium niobate (Ti:PPLN) waveguide are proposed and theoretically investigated. The obtained results confirm full tunability of the SVPGMs. As an example, a 46.5 V applied voltage is required to convert an input vertical vector mode into a horizontal one, accompanied by several L-line singularities, in a 5 mm-long waveguide.
ISSN:2045-2322