Library · Simulation & modelling
What Electromagnetic & Optical Simulation got wrong, from 22 theses
Summary written by a model from the records below: Electromagnetic and optical simulations frequently encounter severe computational bottlenecks when scaling full-wave or ray-tracing approaches to large domains and chaotic structures. Additionally, analytical approximations and idealized geometries often fail because they omit physical effects such as boundary roughness, fabrication imperfections, thin-film interference, and ultra-strong coupling. These records come from graduate theses, 2021 to 2025, each labeled with its degree where the repository states it, and each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Plus 10 problems the authors left open, listed at the end.
Failure modes, by theses reporting them
Select a mode to jump to its records.
Simplified structural and material models fail to capture physical medium complexity
Idealized CAD geometries and homogeneous medium approximations diverged significantly from the behavior of real fabricated nanophotonics and turbid tissues. Omitting fabrication imperfections, local field factors, structural hybridization, or bias-dependent dielectric shifts produced substantial discrepancies in predicted transmission, decorrelation times, and reflectance.
Tried and failed
idealized geometric electromagnetic simulations applied to fabricated nanophotonic transmission spectra. Outcome: did not generalise. Reason: nanoscale fabrication imperfections caused real optical behavior to diverge significantly from idealized CAD geometries
Nonlinear optics in nanoantennas · Imperial · PhD
Tried and failed
dipole-dipole and planar FRET energy transfer models applied to deformable polymer nanoparticle optical sensors. Reason: Dipole-dipole models over-predicted energy transfer efficiency during matrix deswelling, while planar multi-fluorophore models systematically under-predicted it.
Transducing thermodynamic state of water into optical signatures: Applications in synthetic materials and living systems · Cornell · PhD
Lost to a baseline
The published LZ collaboration S2-only toy sensitivity model gave an overly optimistic reach compared to the thesis's more realistic simulation accounting for electron trains and optical propagation
Development of the ionisation signal analysis and the thermometry system for the LUX-ZEPLIN direct dark matter detection experiment · Oxford · PhD
Considered and rejected
Considered and rejected: Rejected using a single gold nanorod geometry in DDA simulations because a T-shaped ligament model better captured localized surface plasmon hybridization and medium dielectric sensitivity.
POLYMER INFILTRATED NANOPOROUS GOLD: KINETICS AND OPTICAL PROPERTIES OF NOVEL POLYMER NANOCOMPOSITES · Penn · PhD
Tried and failed
Analytical diffusion approximation with tissue homogenization applied to turbid media optical decorrelation modeling. Reason: Homogenization and diffusion assumptions produce up to 10x error in electric field decorrelation decay times
Computational optical imaging platform for volumetric large-field studying of cerebral hemodynamics · UT Austin · PhD
Tried and failed
transfer matrix modeling of optical reflectance applied to suspended layered thin film heterostructures. Reason: uncertainties in dielectric functions at high bias voltages caused discrepancies between predicted and measured reflection
Quantum Optics with Excitons in Atomically Thin Semiconductors · Harvard · PhD
Full-wave three-dimensional electromagnetic simulations scale intractably for large optical structures
Methods such as three-dimensional finite-difference time-domain modeling require prohibitive runtime and memory for large metasurfaces, coupled resonator waveguides, and long multimode propagation domains. Researchers rejected or abandoned direct full-wave calculations in favor of split-step Fourier, paraxial, or transmission line approximations to avoid intractable computational costs.
Tried and failed
full-wave electromagnetic simulation applied to millimeter-scale optical metasurfaces. Outcome: infeasible cost. Reason: computational memory and time requirements scale intractably for large-area nanophotonic structures
Multi-functional flat optics for imaging and sensing · MIT · PhD
Considered and rejected
Considered and rejected: Rejected full 3D simulation of planar waveguide polarizability extraction in favor of the TEM waveguide method due to large computational domain and lengthy runtimes (hours to days).
Advanced Metamaterials for Beamforming and Physical Layer Processing · Duke · PhD
Considered and rejected
Considered and rejected: Simulating entire coupled resonator optical waveguides (CROWs) or large rings (R >= 20 um) directly in 3D FDTD, rejected due to prohibitive computational runtime (hours per simulation).
Statistical Modeling of the Effects of Process Variations on Silicon Photonics · MIT · PhD
Considered and rejected
Considered and rejected: Rejected full 3D FDTD simulations for long multimode waveguides due to prohibitive computational costs, using the split-step Fourier method instead.
Programmable Interactions between Optical Fields and Atom-like Systems in Integrated Circuits · MIT · PhD
Considered and rejected
Considered and rejected: Rejected FDTD for long waveguide simulation due to prohibitive computational inefficiency in paraxial propagation.
Development of hybrid optical simulation concepts for polymer waveguides · Leibniz Universität Hannover · PhD
Waveguide approximations break down due to dimensional reduction and neglected boundary interactions
Dimensionally reduced simulations and factored free-space scattering approximations failed when applied to waveguides with boundary roughness perturbations or heterogeneous scatterers. Furthermore, standard formulations generated non-physical reflection coefficients exceeding unity or neglected essential element and waveguide coupling interactions.
Tried and failed
dimensionally reduced 2.5D electromagnetic wave simulation applied to waveguides with boundary roughness perturbations. Reason: boundary perturbations violate vertical mode profile reduction assumptions, causing high error
Adjoint Methods and Inverse Modeling for Process Variation Analysis in Silicon Photonics · MIT · PhD
Tried and failed
factored free-space scattering approximations applied to waveguide attenuation with heterogeneous scatterers. Outcome: did not generalise. Reason: neglects waveguide boundary interactions and non-uniform scatterer spatial distributions causing substantial prediction error
The effect of attenuation from fish on long-range active and passive acoustic sensing in the ocean · Woods Hole · PhD
Considered and rejected
Considered and rejected: Rejected standard travelling-wave formulations for MI waveguides because they predict non-physical reflection coefficients >1 for lossy and out-of-band passive junctions
Near field communication and localisation with slow waves · Imperial · PhD
Ray tracing and analytical scattering approximations fail to account for interference and energy conservation
Geometric ray tracing and first Born scattering approximations neglected critical phenomena such as thin-film interference, cross-field tensor coupling, and beam-axis energy conservation. In addition, ray-tracing software miscalculated optical path difference phase accumulations, leading to severe modeling errors in interferometry and wave scattering.
Tried and failed
spectroscopic modeling neglecting thin-film interference effects applied to nonlinear optical response of thin interfaces. Reason: optical interference and local field factors distort signal escape across polarization geometries
Development and application of electronic sum-frequency generation to molecular solid interfaces · UT Austin · PhD
Tried and failed
geometric ray tracing in turbulent media applied to wave scattering across plasma filaments. Reason: neglects leading-order cross-field coupling term linear in off-diagonal dielectric tensor elements
Impact of wave-filament scattering in the scrape-off layer during lower hybrid current drive · MIT · PhD
Tried and failed
ray-tracing software for relative phase difference simulation applied to optical interferometry and wavefront analysis. Reason: optical path difference phase accumulation was calculated incorrectly, requiring the term to be manually zeroed
Lifetime of beam driven wakes at the FACET-II facility · UT Austin · PhD
Ray-based and high-frequency scattering methods become computationally intractable in complex domains
Monte Carlo ray tracing required excessively large sample sizes to resolve rapid oscillations in three-dimensional propagation, while exact Fermat tracing became intractable under chaotic reflections from curved surfaces. Evaluating transition functions in the Uniform Theory of Diffraction similarly incurred excessive complexity compared to simpler asymptotic diffraction methods.
Tried and failed
Uniform Theory of Diffraction modeling applied to large-scale optical scattering simulation. Outcome: too slow. Reason: Excessive computational complexity in evaluating transition functions for large-scale structures compared to simpler asymptotic diffraction approximations.
Metrology of high aspect ratio nanoelectromechanical systems (NEMS) · Imperial · PhD
Tried and failed
exact Fermat ray tracing with circular reflections applied to optical path computation. Outcome: infeasible cost. Reason: chaotic scattering from curved reflective surfaces made exact computation computationally intractable
INFORMATION-DRIVEN MULTI-VIEW PATH PLANNING FOR UNDERWATER TARGET RECOGNITION · Cornell · PhD
Modal and analytical frameworks break down in strong coupling and multi-mode dissipation regimes
Classical coupled mode theory failed in the ultra-strong coupling regime because the rotating wave approximation omitted necessary frequency-dependent off-diagonal corrections. Similarly, variational conductivity models failed to capture spectral dissipation and smearing, while iterative phase retrieval algorithms could not resolve parasitic multi-path side pulses in multimode waveguides.
Lost to a baseline
Variational FHIP optical conductivity spectra produce unbroadened multi-phonon Franck-Condon peaks, failing to match the smearing/dissipation captured by Diagrammatic Monte Carlo (DiagMC).
Path integral methods for polarons in real materials · Imperial · Doctorate
Tried and failed
classical coupled mode theory applied to ultrastrongly coupled optical resonators. Reason: rotating wave approximation fails in the ultra-strong coupling regime without frequency-dependent off-diagonal corrections
Subwavelength optical resonators for efficient modulation of two-dimensional semiconductor excitonic properties · UT Austin · PhD
Tried and failed
Iterative phase retrieval and gradient optimization applied to multi-mode waveguide pulse reconstruction. Outcome: did not generalise. Reason: Higher-order mode reconstruction could not account for parasitic multi-path side pulses
Terahertz ultrafast optics for bandstructure engineering · UT Austin · PhD
Left open by the authors
Problems the authors named and did not get to.
Left open
Perform FDTD simulations of the optical probe system to model phase accumulation and resolve Code V optical path difference discrepancies. Blocker: None
Lifetime of beam driven wakes at the FACET-II facility · UT Austin · PhD
Left open
Refine the fiber Bragg grating spectral analysis model by implementing anisotropic dielectric perturbation tensors and modal deformation calculations. Blocker: None
Investigation of Bragg Gratings in Few-Mode Fibers with a Femtosecond Laser Point-by-Point Technique · Virginia Tech · Doctorate
Left open
Simulate vertical coupling in stacked nanodisks separated by dielectric films to model an anapole nanotower using FDTD and multipole decomposition. Blocker: None
Strong coupling in nanoplasmonic systems, and anapoles · Imperial · PhD
Left open
Simulate coupled Maxwell-heat equations to determine transverse mode instability power thresholds in scaled short optical fibers. Blocker: Requires access to the thesis author's specialized parallel hp-adaptive DPG finite element codebase.
A scalable hp-adaptive finite element software with applications in fiber optics · UT Austin · PhD
Left open
Implement time-domain adjoint topology optimization using FDTD to design photonic crystal waveguides for pulse shaping, pulse delay, and particle acceleration. Blocker: None
Topology Optimization for Dispersive (3D) Meta‑Optics via the Time‑Domain Adjoint Method using FDTD and High‑Performance Computing · Leibniz Universität Hannover · PhD
Left open
Model the full diffraction orders and reflectance bandwidth for 2D self-assembled periodic nanocolumns using standard optical simulation tools. Blocker: None
Magnetically responsive dynamic nanostructures · UT Austin · PhD
Left open
Extend the CCPR-ADE time-domain adjoint dissipation framework and analytical gradient evaluation to nonlinear optical media in FDTD. Blocker: None
Topology Optimization for Dispersive (3D) Meta‑Optics via the Time‑Domain Adjoint Method using FDTD and High‑Performance Computing · Leibniz Universität Hannover · PhD
Left open
Extend the HEDA optical extinction model to 2D or 3D anisotropic plasmonic nanocrystal geometries. Blocker: Generalizing Mie theory/Maxwell-Garnett core-shell approximation to multi-dimensional anisotropic geometries requires developing or integrating numerical electrodynamics solvers without explicit formulation provided.
Nonuniform charge carrier distribution within plasmonic semiconductor nanocrystals · UT Austin · PhD
Left open
Develop a deep learning FDTR model taking optical parameters, sample layering geometry, and phase lag data simultaneously as inputs to predict thermal properties. Blocker: None
Investigation of memristor devices and materials through multi-scale modeling and metrology · Georgia Tech · PhD
Left open
Develop theoretical formalism and numerical simulation for multi-tonal Floquet-Fresnel optical reflectivity accounting for finite mode lifetimes. Blocker: None
Parametric resonances in Floquet materials · Harvard · PhD
Who has worked on this
Authors of the public theses cited on this page, most-cited first.
- Johannes Gedeon · Leibniz Universität Hannover · PhD · 2025
Topology Optimization for Dispersive (3D) Meta‑Optics via the Time‑Domain Adjoint Method using FDTD and High‑Performance Computing - Bradley Martin · Imperial · Doctorate · 2024
Path integral methods for polarons in real materials - Hugo Larocque · MIT · PhD · 2024
Programmable Interactions between Optical Fields and Atom-like Systems in Integrated Circuits - John Yang · Imperial · PhD · 2024
Nonlinear optics in nanoantennas - Weiwei Kong · Penn · PhD · 2024
POLYMER INFILTRATED NANOPOROUS GOLD: KINETICS AND OPTICAL PROPERTIES OF NOVEL POLYMER NANOCOMPOSITES - Peter Fox · Imperial · PhD · 2023
Strong coupling in nanoplasmonic systems, and anapoles - Fan Yang · MIT · PhD · 2023
Multi-functional flat optics for imaging and sensing - Artem Voronov · Imperial · PhD · 2023
Near field communication and localisation with slow waves - Piyush Jain · Cornell · PhD · 2023
Transducing thermodynamic state of water into optical signatures: Applications in synthetic materials and living systems - Zhengxing Zhang · MIT · PhD · 2023
Adjoint Methods and Inverse Modeling for Process Variation Analysis in Silicon Photonics - Frederic Kwan · Imperial · PhD · 2023
Metrology of high aspect ratio nanoelectromechanical systems (NEMS) - Divya Pande · Duke · PhD · 2023
Advanced Metamaterials for Beamforming and Physical Layer Processing
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