@article{3847,
  abstract     = {{Sheets of slab waveguides with sharp corners are investigated. By means of rigorous
numerical experiments, we look at oblique incidence of semi-guided plane waves. Radiation losses
vanish beyond a certain critical angle of incidence. One can thus realize lossless propagation through
90-degree corner configurations, where the remaining guided waves are still subject to pronounced
reflection and polarization conversion. A system of two corners can be viewed as a structure akin to
a Fabry-Perot-interferometer. By adjusting the distance between the two partial reflectors, here the
90-degree corners, one identifies step-like configurations that transmit the semi-guided plane waves
without radiation losses, and virtually without reflections. Simulations of semi-guided beams with
in-plane wide Gaussian profiles show that the effect survives in a true 3-D framework.}},
  author       = {{Hammer, Manfred and Hildebrandt, Andre and Förstner, Jens}},
  issn         = {{0733-8724}},
  journal      = {{Journal of Lightwave Technology}},
  keywords     = {{tet_topic_waveguide}},
  number       = {{3}},
  pages        = {{997--1005}},
  publisher    = {{Institute of Electrical and Electronics Engineers (IEEE)}},
  title        = {{{Full Resonant Transmission of Semiguided Planar Waves Through Slab Waveguide Steps at Oblique Incidence}}},
  doi          = {{10.1109/jlt.2015.2502431}},
  volume       = {{34}},
  year         = {{2015}},
}

@article{3894,
  abstract     = {{We show how to optically connect guiding layers at different elevations in a 3-D integrated photonic circuit. Transfer of
optical power carried by planar, semi-guided waves is possible without reflections or radiation losses, and over large
vertical distances. This functionality is realized through simple step-like folds of high-contrast dielectric slab waveguides, in combination with oblique wave incidence, and fulfilling a resonance condition. Radiation losses vanish, and polarization conversion is suppressed for TE wave incidence beyond certain critical angles. This can be understood by fundamental arguments resting on a version of Snell’s law. The two 90° corners of a step act as identical partial reflectors in a Fabry–Perot-like resonator setup. By selecting the step height, i.e., the distance between the reflectors, one realizes resonant states with full transmission. Rigorous quasi-analytical simulations
for typical silicon/silica parameters demonstrate the functioning. Combinations of several step junctions can lead
to other types of optical on-chip connects, e.g., U-turn- or bridge-like configurations.}},
  author       = {{Hammer, Manfred and Hildebrandt, Andre and Förstner, Jens}},
  issn         = {{0146-9592}},
  journal      = {{Optics Letters}},
  keywords     = {{tet_topic_waveguide}},
  number       = {{16}},
  pages        = {{3711--3714}},
  publisher    = {{The Optical Society}},
  title        = {{{How planar optical waves can be made to climb dielectric steps}}},
  doi          = {{10.1364/ol.40.003711}},
  volume       = {{40}},
  year         = {{2015}},
}

@article{3890,
  abstract     = {{The incidenceofthin-film-guided, in-planeunguidedwavesatobliqueanglesonstraightdiscontinuities of dielectricslabwaveguides,anearlyproblemofintegratedoptics,isbeingre-considered.The3-D frequencydomainMaxwellequationsreducetoaparametrizedinhomogeneousvectorialproblemona
2-D computationaldomain,withtransparent-influx boundaryconditions.Weproposearigorousvec-
torial solverbasedonsimultaneousexpansionsintopolarizedlocalslabeigenmodesalongthetwo
orthogonal crosssectioncoordinates(quadridirectionaleigenmodepropagationQUEP).Thequasi-ana-
lytical schemeisapplicabletoconfigurations with — in principle — arbitrary crosssectiongeometries.
Examples forahigh-contrastfacetofanasymmetricslabwaveguide,forthelateralexcitationofa
channel waveguide,andforastepdiscontinuitybetweenslabwaveguidesofdifferentthicknessesare
discussed.}},
  author       = {{Hammer, Manfred}},
  issn         = {{0030-4018}},
  journal      = {{Optics Communications}},
  keywords     = {{tet_topic_waveguide, tet_topic_numerics}},
  pages        = {{447--456}},
  publisher    = {{Elsevier BV}},
  title        = {{{Oblique incidence of semi-guided waves on rectangular slab waveguide discontinuities: A vectorial QUEP solver}}},
  doi          = {{10.1016/j.optcom.2014.09.087}},
  volume       = {{338}},
  year         = {{2014}},
}

@article{3937,
  abstract     = {{The relevance of our definition for sensitivity in refractometric sensing, being the relative change in the transmittance
of a certain output channel of an optical device over the change in the refractive index of the probed
material, is discussed. It is compared to one based on spectral shift per refractive index unit change. Further, there
is discussion on how group delay and sensitivity are interrelated and can be converted into each other and which
physical quantities are relevant for high sensitivity. As a by-product of the theory presented, a general expression
relating group delay and the ratio of the time-averaged optical energy and the input power is presented.}},
  author       = {{Hoekstra, Hugo J. W. M. and Hammer, Manfred}},
  issn         = {{0740-3224}},
  journal      = {{Journal of the Optical Society of America B}},
  keywords     = {{tet_topic_waveguide}},
  number       = {{7}},
  publisher    = {{The Optical Society}},
  title        = {{{General relation for group delay and the relevance of group delay for refractometric sensing}}},
  doi          = {{10.1364/josab.31.001561}},
  volume       = {{31}},
  year         = {{2014}},
}