{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/134225"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/134225","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Optimizing GPU Performance in Cylindrical FDTD Simulations","abstract":"Simulating large-area metasurfaces presents a major computational challenge due to their fine structural features and large physical dimensions. Traditional full-wave methods, such as finite-difference time-domain (FDTD), become infeasible for such problems due to excessive memory and runtime requirements. To address this, several approximate techniques have been developed, including the localized perturbation approximation (LPA), overlapping-domain approximation (ODA), and zoned discrete axisymmetry (ZDA), each balancing accuracy and efficiency for different metasurface geometries. In this thesis, we focus on ZDA, a method tailored for metasurfaces with rotational symmetry. By expressing electromagnetic fields as a sum of angular modes and discretizing the radial domain into concentric zones, ZDA reduces a 3D problem to a series of much smaller and fewer simulations. This dimensionality reduction enables accurate modeling of freeform optical devices with fine resolution using modest computational resources. We implement this approach via a GPU-accelerated FDTD solver in cylindrical coordinates, enabling scalable and efficient simulation of broadband, high-performance metasurfaces. Our results demonstrate that symmetry-aligned simulation strategies such as ZDA can unlock practical design workflows for metasurfaces previously beyond reach. My personal work though was mostly on accelerating our FDTD code using the power given by the GPUs.","abstract_html":"Simulating large-area metasurfaces presents a major computational challenge due to their fine structural features and large physical dimensions. Traditional full-wave methods, such as finite-difference time-domain (FDTD), become infeasible for such problems due to excessive memory and runtime requirements. To address this, several approximate techniques have been developed, including the localized perturbation approximation (LPA), overlapping-domain approximation (ODA), and zoned discrete axisymmetry (ZDA), each balancing accuracy and efficiency for different metasurface geometries. In this thesis, we focus on ZDA, a method tailored for metasurfaces with rotational symmetry. By expressing electromagnetic fields as a sum of angular modes and discretizing the radial domain into concentric zones, ZDA reduces a 3D problem to a series of much smaller and fewer simulations. This dimensionality reduction enables accurate modeling of freeform optical devices with fine resolution using modest computational resources. We implement this approach via a GPU-accelerated FDTD solver in cylindrical coordinates, enabling scalable and efficient simulation of broadband, high-performance metasurfaces. Our results demonstrate that symmetry-aligned simulation strategies such as ZDA can unlock practical design workflows for metasurfaces previously beyond reach. My personal work though was mostly on accelerating our FDTD code using the power given by the GPUs.","abstract_has_math":false,"creators":["Giannakopoulos, Dimitrios"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Computer Engineering","degree_department":"Electrical and Computer Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Lin, Zin"],"committee_members":["Stavrou, Angelos","Raghunathan, Ravi"],"year":2025,"date_issued":"2025-05-23","date_published":"2025-05-23","updated_at":"2026-07-22T22:19:15Z","subjects":["FDTD","axial symmetry","metasurface","GPU","Julia","Parallelization"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:44108"],"render_values":[{"text":"vt_gsexam:44108","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/134225","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Lin, Zin"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Stavrou, Angelos","Raghunathan, Ravi"]},{"key":"dc:contributor.department","label":"Department","values":["Electrical and Computer Engineering"]},{"key":"dc:creator","label":"Author","values":["Giannakopoulos, Dimitrios"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-05-24T08:04:50Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-05-24T08:04:50Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-05-23"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Computer Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["FDTD","axial symmetry","metasurface","GPU","Julia","Parallelization"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:44108"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/134225"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Simulating large-area metasurfaces presents a major computational challenge due to their fine structural features and large physical dimensions. Traditional full-wave methods, such as finite-difference time-domain (FDTD), become infeasible for such problems due to excessive memory and runtime requirements. To address this, several approximate techniques have been developed, including the localized perturbation approximation (LPA), overlapping-domain approximation (ODA), and zoned discrete axisymmetry (ZDA), each balancing accuracy and efficiency for different metasurface geometries. In this thesis, we focus on ZDA, a method tailored for metasurfaces with rotational symmetry. By expressing electromagnetic fields as a sum of angular modes and discretizing the radial domain into concentric zones, ZDA reduces a 3D problem to a series of much smaller and fewer simulations. This dimensionality reduction enables accurate modeling of freeform optical devices with fine resolution using modest computational resources. We implement this approach via a GPU-accelerated FDTD solver in cylindrical coordinates, enabling scalable and efficient simulation of broadband, high-performance metasurfaces. Our results demonstrate that symmetry-aligned simulation strategies such as ZDA can unlock practical design workflows for metasurfaces previously beyond reach. My personal work though was mostly on accelerating our FDTD code using the power given by the GPUs."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Simulating how light interacts with large, complex optical surfaces, known as metasurfaces, is essential for designing new technologies like ultra-thin lenses. These surfaces often span millimeters in size but contain tiny features measured in nanometers, making them extremely difficult to model with standard simulation tools. The most accurate methods, such as finite-difference time-domain (FDTD), quickly become too slow and memory-intensive for practical use at this scale. In this project, the focus was on making these simulations faster and more efficient. I worked on accelerating the FDTD method that takes advantage of the symmetrical shape of certain metasurfaces. This involved adapting the simulation to cylindrical coordinates and running it on graphics processors (GPUs), which are well-suited for high-speed parallel computation. The result is a simulation tool that can handle large-area metasurfaces with much lower computing cost opens the door to faster design cycles and more ambitious optical applications."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Optimizing GPU Performance in Cylindrical FDTD Simulations"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Lin, Zin"],"dc:contributor.committeemember":["Stavrou, Angelos","Raghunathan, Ravi"],"dc:contributor.department":["Electrical and Computer Engineering"],"dc:creator":["Giannakopoulos, Dimitrios"],"dc:date.accessioned":["2025-05-24T08:04:50Z"],"dc:date.available":["2025-05-24T08:04:50Z"],"dc:date.issued":["2025-05-23"],"dc:description.abstract":["Simulating large-area metasurfaces presents a major computational challenge due to their fine structural features and large physical dimensions. Traditional full-wave methods, such as finite-difference time-domain (FDTD), become infeasible for such problems due to excessive memory and runtime requirements. To address this, several approximate techniques have been developed, including the localized perturbation approximation (LPA), overlapping-domain approximation (ODA), and zoned discrete axisymmetry (ZDA), each balancing accuracy and efficiency for different metasurface geometries. In this thesis, we focus on ZDA, a method tailored for metasurfaces with rotational symmetry. By expressing electromagnetic fields as a sum of angular modes and discretizing the radial domain into concentric zones, ZDA reduces a 3D problem to a series of much smaller and fewer simulations. This dimensionality reduction enables accurate modeling of freeform optical devices with fine resolution using modest computational resources. We implement this approach via a GPU-accelerated FDTD solver in cylindrical coordinates, enabling scalable and efficient simulation of broadband, high-performance metasurfaces. Our results demonstrate that symmetry-aligned simulation strategies such as ZDA can unlock practical design workflows for metasurfaces previously beyond reach. My personal work though was mostly on accelerating our FDTD code using the power given by the GPUs."],"dc:description.abstractgeneral":["Simulating how light interacts with large, complex optical surfaces, known as metasurfaces, is essential for designing new technologies like ultra-thin lenses. These surfaces often span millimeters in size but contain tiny features measured in nanometers, making them extremely difficult to model with standard simulation tools. The most accurate methods, such as finite-difference time-domain (FDTD), quickly become too slow and memory-intensive for practical use at this scale. In this project, the focus was on making these simulations faster and more efficient. I worked on accelerating the FDTD method that takes advantage of the symmetrical shape of certain metasurfaces. This involved adapting the simulation to cylindrical coordinates and running it on graphics processors (GPUs), which are well-suited for high-speed parallel computation. The result is a simulation tool that can handle large-area metasurfaces with much lower computing cost opens the door to faster design cycles and more ambitious optical applications."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:44108"],"dc:identifier.uri":["https://hdl.handle.net/10919/134225"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["FDTD","axial symmetry","metasurface","GPU","Julia","Parallelization"],"dc:title":["Optimizing GPU Performance in Cylindrical FDTD Simulations"],"dc:type":["Thesis"],"thesis:degree_discipline":["Computer Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:15Z"}