@article{60891,
  abstract     = {{Straight dielectric waveguide channels made from slabs of thin-film lithium niobate (TFLN), or lithium niobate on insulator (LNOI), are investigated in the linear regime, for channels of rib and strip type with common trapezoidal cross sections, in Z-cut and X-cut samples at varying on-chip orientation. We clarify the theoretical basis for the waveguides with potentially non-diagonal core permittivity. Symmetry classes can be distinguished that differ in their consequences for potential modal degeneracy and polarization conversion. Our rigorous numerical analysis by means of a finite-element solver takes the anisotropy of the lithium niobate cores rigorously into account. We discuss extensive data for effective indices, polarization properties, and hybridization of guided modes, in single- and multimode channels. Scans over the waveguide width and orientation as primary parameters are complemented by a series of illustrations of vectorial mode profiles. These turn out to be essentially complex in cases of X-cut channels at non-crystal-axis-aligned orientations.}},
  author       = {{Hammer, Manfred and Khan, Shahriar and Taheri, Behnood and Farheen, Henna and Förstner, Jens}},
  issn         = {{2770-0208}},
  journal      = {{Optics Continuum}},
  keywords     = {{tet_topic_waveguide}},
  number       = {{10}},
  pages        = {{2356}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{TFLN channel waveguides of rib and strip type: Properties of guided modes}}},
  doi          = {{10.1364/optcon.569959}},
  volume       = {{4}},
  year         = {{2025}},
}

@article{59069,
  abstract     = {{<jats:p>Stable and bright single photon sources are key components for future quantum applications. A simple fabrication method is an important requirement for such sources. Here, we present a single photon source based on diced ridge waveguides in titanium indiffused LiNbO<jats:sub>3</jats:sub>. These waveguides can be easily fabricated by combining planar titanium in-diffusion without lithographic patterning and easy-to-handle precision dicing. Such devices have the potential to generate high single photon rates because ridge structures are typically less prone to the photorefractive effect. We achieve waveguide propagation losses &lt;0.4dBcm and a SHG conversion efficiency of about 81%Wcm<jats:sup>2</jats:sup>. Harnessing a type-0 SPDC process to generate 1550 nm photons, we obtain a SPDC brightness of 3⋅10<jats:sup>5</jats:sup>1s⋅mW⋅nm, with a heralding efficiency of <jats:italic>η</jats:italic><jats:sub>h</jats:sub>=45% (<jats:italic>η</jats:italic><jats:sub>h,wg</jats:sub>=77.5% for the waveguide itself excluded setup losses) and a heralded second-order correlation function of <jats:italic>g</jats:italic><jats:sub>h</jats:sub><jats:sup>2</jats:sup>(0)&lt;0.003 at low pump powers.</jats:p>}},
  author       = {{Kießler, Christian and Kirsch, Michelle and Lengeling, Sebastian and Herrmann, Harald and Silberhorn, Christine}},
  issn         = {{2770-0208}},
  journal      = {{Optics Continuum}},
  number       = {{3}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{SPDC single-photon source in Ti-indiffused diced ridge LiNbO<sub>3</sub> waveguides}}},
  doi          = {{10.1364/optcon.557439}},
  volume       = {{4}},
  year         = {{2025}},
}

@article{56193,
  abstract     = {{Dielectric slab waveguides made of thin-film-lithium-niobate (TFLN) media are consid-ered, for operation in the linear regime. We outline and implement a largely analytic procedure forrigorous modal analysis of three-layer slabs with birefringent, anisotropic core. For Z-cut wave-guides, the slab eigenmode problem separates into uncoupled sets of scalar equations for TE andTM modes. Slabs in X-cut configuration support mostly mildly hybrid eigenmodes, with clear pre-dominant TE or TM polarization, and with effective indices that depend on the propagation directionof the modes, relative to the crystal axes. Strong hybridization can be observed for near degeneratemodes in singular configurations without vertical symmetry, or in symmetric slabs where two nearlydegenerate modes are of the same symmetry class. Dispersion curves for slab thickness and propa-gation angle are discussed, for slabs with oxide and air cover. }},
  author       = {{Hammer, Manfred and Farheen, Henna and Förstner, Jens}},
  issn         = {{2770-0208}},
  journal      = {{Optics Continuum}},
  keywords     = {{tet_topic_waveguide}},
  pages        = {{532822}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Guided modes of thin-film lithium niobate slabs}}},
  doi          = {{10.1364/optcon.532822}},
  year         = {{2024}},
}