--- _id: '52700' abstract: - lang: eng text: 'We explore the polarization hysteretic behaviour and field-dependent permittivity of ferroelectric-dielectric 2D materials formed by random dispersions of low permittivity inclusions in a ferroelectric matrix, using finite element simulations. We show how the degree of impenetrability of dielectric inclusions plays a substantial role in controlling the coercive field, remnant and saturation polarizations of the homogenized materials. The results highlight the significance of the degree of impenetrability of inclusion in tuning the effective polarization properties of such ferroelectric composites: coercive field drops significantly as percolation threshold is attained and remnant polarization decreases faster than a linear decay.' author: - first_name: Viktor full_name: Myroshnychenko, Viktor id: '46371' last_name: Myroshnychenko - first_name: Pious Mathews full_name: Mulavarickal Jose, Pious Mathews last_name: Mulavarickal Jose - first_name: Henna full_name: Farheen, Henna last_name: Farheen - first_name: Shafaq full_name: Ejaz, Shafaq last_name: Ejaz - first_name: Christian full_name: Brosseau, Christian last_name: Brosseau - first_name: Jens full_name: Förstner, Jens id: '158' last_name: Förstner orcid: 0000-0001-7059-9862 citation: ama: 'Myroshnychenko V, Mulavarickal Jose PM, Farheen H, Ejaz S, Brosseau C, Förstner J. From Swiss-cheese to discrete ferroelectric composites: assessing the ferroelectric butterfly shape in polarization loops. Physica Scripta. 2024;99(4):045952. doi:10.1088/1402-4896/ad3172' apa: 'Myroshnychenko, V., Mulavarickal Jose, P. M., Farheen, H., Ejaz, S., Brosseau, C., & Förstner, J. (2024). From Swiss-cheese to discrete ferroelectric composites: assessing the ferroelectric butterfly shape in polarization loops. Physica Scripta, 99(4), 045952. https://doi.org/10.1088/1402-4896/ad3172' bibtex: '@article{Myroshnychenko_Mulavarickal Jose_Farheen_Ejaz_Brosseau_Förstner_2024, title={From Swiss-cheese to discrete ferroelectric composites: assessing the ferroelectric butterfly shape in polarization loops}, volume={99}, DOI={10.1088/1402-4896/ad3172}, number={4}, journal={Physica Scripta}, publisher={IOP Publishing}, author={Myroshnychenko, Viktor and Mulavarickal Jose, Pious Mathews and Farheen, Henna and Ejaz, Shafaq and Brosseau, Christian and Förstner, Jens}, year={2024}, pages={045952} }' chicago: 'Myroshnychenko, Viktor, Pious Mathews Mulavarickal Jose, Henna Farheen, Shafaq Ejaz, Christian Brosseau, and Jens Förstner. “From Swiss-Cheese to Discrete Ferroelectric Composites: Assessing the Ferroelectric Butterfly Shape in Polarization Loops.” Physica Scripta 99, no. 4 (2024): 045952. https://doi.org/10.1088/1402-4896/ad3172.' ieee: 'V. Myroshnychenko, P. M. Mulavarickal Jose, H. Farheen, S. Ejaz, C. Brosseau, and J. Förstner, “From Swiss-cheese to discrete ferroelectric composites: assessing the ferroelectric butterfly shape in polarization loops,” Physica Scripta, vol. 99, no. 4, p. 045952, 2024, doi: 10.1088/1402-4896/ad3172.' mla: 'Myroshnychenko, Viktor, et al. “From Swiss-Cheese to Discrete Ferroelectric Composites: Assessing the Ferroelectric Butterfly Shape in Polarization Loops.” Physica Scripta, vol. 99, no. 4, IOP Publishing, 2024, p. 045952, doi:10.1088/1402-4896/ad3172.' short: V. Myroshnychenko, P.M. Mulavarickal Jose, H. Farheen, S. Ejaz, C. Brosseau, J. Förstner, Physica Scripta 99 (2024) 045952. date_created: 2024-03-21T10:34:48Z date_updated: 2024-03-21T10:40:51Z ddc: - '530' department: - _id: '61' - _id: '230' doi: 10.1088/1402-4896/ad3172 file: - access_level: open_access content_type: application/pdf creator: fossie date_created: 2024-03-21T10:39:32Z date_updated: 2024-03-21T10:39:32Z file_id: '52701' file_name: 2024-03 Myroshnychenko - Physica Scripta - From Swiss-cheese to discrete ferroelectric.pdf file_size: 5386508 relation: main_file file_date_updated: 2024-03-21T10:39:32Z has_accepted_license: '1' intvolume: ' 99' issue: '4' keyword: - tet_topic_ferro language: - iso: eng oa: '1' page: '045952' project: - _id: '52' name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing' publication: Physica Scripta publication_identifier: issn: - 0031-8949 - 1402-4896 publication_status: published publisher: IOP Publishing status: public title: 'From Swiss-cheese to discrete ferroelectric composites: assessing the ferroelectric butterfly shape in polarization loops' type: journal_article user_id: '158' volume: 99 year: '2024' ... --- _id: '43018' article_number: '108557' author: - first_name: Samer full_name: Alhaddad, Samer id: '42456' last_name: Alhaddad - first_name: Jens full_name: Förstner, Jens id: '158' last_name: Förstner orcid: 0000-0001-7059-9862 - first_name: Yevgen full_name: Grynko, Yevgen id: '26059' last_name: Grynko citation: ama: Alhaddad S, Förstner J, Grynko Y. Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength. Journal of Quantitative Spectroscopy and Radiative Transfer. 2023;302. doi:10.1016/j.jqsrt.2023.108557 apa: Alhaddad, S., Förstner, J., & Grynko, Y. (2023). Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength. Journal of Quantitative Spectroscopy and Radiative Transfer, 302, Article 108557. https://doi.org/10.1016/j.jqsrt.2023.108557 bibtex: '@article{Alhaddad_Förstner_Grynko_2023, title={Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength}, volume={302}, DOI={10.1016/j.jqsrt.2023.108557}, number={108557}, journal={Journal of Quantitative Spectroscopy and Radiative Transfer}, publisher={Elsevier BV}, author={Alhaddad, Samer and Förstner, Jens and Grynko, Yevgen}, year={2023} }' chicago: Alhaddad, Samer, Jens Förstner, and Yevgen Grynko. “Numerical Study of Light Backscattering from Layers of Absorbing Irregular Particles Larger than the Wavelength.” Journal of Quantitative Spectroscopy and Radiative Transfer 302 (2023). https://doi.org/10.1016/j.jqsrt.2023.108557. ieee: 'S. Alhaddad, J. Förstner, and Y. Grynko, “Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength,” Journal of Quantitative Spectroscopy and Radiative Transfer, vol. 302, Art. no. 108557, 2023, doi: 10.1016/j.jqsrt.2023.108557.' mla: Alhaddad, Samer, et al. “Numerical Study of Light Backscattering from Layers of Absorbing Irregular Particles Larger than the Wavelength.” Journal of Quantitative Spectroscopy and Radiative Transfer, vol. 302, 108557, Elsevier BV, 2023, doi:10.1016/j.jqsrt.2023.108557. short: S. Alhaddad, J. Förstner, Y. Grynko, Journal of Quantitative Spectroscopy and Radiative Transfer 302 (2023). date_created: 2023-03-14T12:32:54Z date_updated: 2023-03-15T17:36:13Z ddc: - '530' department: - _id: '61' doi: 10.1016/j.jqsrt.2023.108557 file: - access_level: local content_type: application/pdf creator: fossie date_created: 2023-03-15T15:58:15Z date_updated: 2023-03-15T15:58:15Z file_id: '43028' file_name: 2023-03 Alhaddad - JQSRT - Numerical study of light backscattering from layers of absorbing particles larger than the wavelength.pdf file_size: 1508833 relation: main_file - access_level: open_access content_type: application/pdf creator: fossie date_created: 2023-03-15T17:35:29Z date_updated: 2023-03-15T17:35:29Z file_id: '43029' file_name: 2023-03 Alhaddad - JQSRT - Numerical study of light backscattering from layers of absorbing particles larger than the wavelength (accepted manuscript).pdf file_size: 4254386 relation: main_file file_date_updated: 2023-03-15T17:35:29Z has_accepted_license: '1' intvolume: ' 302' keyword: - tet_topic_scattering language: - iso: eng oa: '1' project: - _id: '52' name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing' publication: Journal of Quantitative Spectroscopy and Radiative Transfer publication_identifier: issn: - 0022-4073 publication_status: published publisher: Elsevier BV status: public title: Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength type: journal_article user_id: '158' volume: 302 year: '2023' ... --- _id: '43051' abstract: - lang: eng text: We demonstrate the numerical and experimental realization of optimized optical traveling-wave antennas made of low-loss dielectric materials. These antennas exhibit highly directive radiation patterns and our studies reveal that this nature comes from two dominant guided TE modes excited in the waveguide-like director of the antenna, in addition to the leaky modes. The optimized antennas possess a broadband nature and have a nearunity radiation efficiency at an operational wavelength of 780 nm. Compared to the previously studied plasmonic antennas for photon emission, our all-dielectric approach demonstrates a new class of highly directional, low-loss, and broadband optical antennas. author: - first_name: Henna full_name: Farheen, Henna last_name: Farheen - first_name: Lok-Yee full_name: Yan, Lok-Yee last_name: Yan - first_name: Till full_name: Leuteritz, Till last_name: Leuteritz - first_name: Siqi full_name: Qiao, Siqi last_name: Qiao - first_name: Florian full_name: Spreyer, Florian last_name: Spreyer - first_name: Christian full_name: Schlickriede, Christian last_name: Schlickriede - first_name: Viktor full_name: Quiring, Viktor last_name: Quiring - first_name: Christof full_name: Eigner, Christof last_name: Eigner - first_name: Christine full_name: Silberhorn, Christine id: '26263' last_name: Silberhorn - first_name: Thomas full_name: Zentgraf, Thomas id: '30525' last_name: Zentgraf orcid: 0000-0002-8662-1101 - first_name: Stefan full_name: Linden, Stefan last_name: Linden - first_name: Viktor full_name: Myroshnychenko, Viktor id: '46371' last_name: Myroshnychenko - first_name: Jens full_name: Förstner, Jens id: '158' last_name: Förstner orcid: 0000-0001-7059-9862 citation: ama: 'Farheen H, Yan L-Y, Leuteritz T, et al. Tailoring the directive nature of optical waveguide antennas. In: García-Blanco SM, Cheben P, eds. Integrated Optics: Devices, Materials, and Technologies XXVII. SPIE; 2023:124241E. doi:10.1117/12.2658921' apa: 'Farheen, H., Yan, L.-Y., Leuteritz, T., Qiao, S., Spreyer, F., Schlickriede, C., Quiring, V., Eigner, C., Silberhorn, C., Zentgraf, T., Linden, S., Myroshnychenko, V., & Förstner, J. (2023). Tailoring the directive nature of optical waveguide antennas. In S. M. García-Blanco & P. Cheben (Eds.), Integrated Optics: Devices, Materials, and Technologies XXVII (p. 124241E). SPIE. https://doi.org/10.1117/12.2658921' bibtex: '@inproceedings{Farheen_Yan_Leuteritz_Qiao_Spreyer_Schlickriede_Quiring_Eigner_Silberhorn_Zentgraf_et al._2023, title={Tailoring the directive nature of optical waveguide antennas}, DOI={10.1117/12.2658921}, booktitle={Integrated Optics: Devices, Materials, and Technologies XXVII}, publisher={SPIE}, author={Farheen, Henna and Yan, Lok-Yee and Leuteritz, Till and Qiao, Siqi and Spreyer, Florian and Schlickriede, Christian and Quiring, Viktor and Eigner, Christof and Silberhorn, Christine and Zentgraf, Thomas and et al.}, editor={García-Blanco, Sonia M. and Cheben, Pavel}, year={2023}, pages={124241E} }' chicago: 'Farheen, Henna, Lok-Yee Yan, Till Leuteritz, Siqi Qiao, Florian Spreyer, Christian Schlickriede, Viktor Quiring, et al. “Tailoring the Directive Nature of Optical Waveguide Antennas.” In Integrated Optics: Devices, Materials, and Technologies XXVII, edited by Sonia M. García-Blanco and Pavel Cheben, 124241E. SPIE, 2023. https://doi.org/10.1117/12.2658921.' ieee: 'H. Farheen et al., “Tailoring the directive nature of optical waveguide antennas,” in Integrated Optics: Devices, Materials, and Technologies XXVII, 2023, p. 124241E, doi: 10.1117/12.2658921.' mla: 'Farheen, Henna, et al. “Tailoring the Directive Nature of Optical Waveguide Antennas.” Integrated Optics: Devices, Materials, and Technologies XXVII, edited by Sonia M. García-Blanco and Pavel Cheben, SPIE, 2023, p. 124241E, doi:10.1117/12.2658921.' short: 'H. Farheen, L.-Y. Yan, T. Leuteritz, S. Qiao, F. Spreyer, C. Schlickriede, V. Quiring, C. Eigner, C. Silberhorn, T. Zentgraf, S. Linden, V. Myroshnychenko, J. Förstner, in: S.M. García-Blanco, P. Cheben (Eds.), Integrated Optics: Devices, Materials, and Technologies XXVII, SPIE, 2023, p. 124241E.' date_created: 2023-03-21T12:28:31Z date_updated: 2023-03-22T09:26:25Z ddc: - '530' department: - _id: '61' - _id: '230' - _id: '429' doi: 10.1117/12.2658921 editor: - first_name: Sonia M. full_name: García-Blanco, Sonia M. last_name: García-Blanco - first_name: Pavel full_name: Cheben, Pavel last_name: Cheben file: - access_level: local content_type: application/pdf creator: fossie date_created: 2023-03-22T09:25:57Z date_updated: 2023-03-22T09:25:57Z file_id: '43062' file_name: 2023-01 Poster Photonics West Henna OWA_A0.pdf file_size: 1426599 relation: main_file file_date_updated: 2023-03-22T09:25:57Z has_accepted_license: '1' keyword: - tet_topic_opticalantenna language: - iso: eng page: 124241E publication: 'Integrated Optics: Devices, Materials, and Technologies XXVII' publication_status: published publisher: SPIE status: public title: Tailoring the directive nature of optical waveguide antennas type: conference user_id: '158' year: '2023' ... --- _id: '43052' abstract: - lang: eng text: We demonstrate a large-scale two dimensional silicon-based optical phased array (OPA) composed of nanoantennas with circular gratings that are balanced in power and aligned in phase, required for producing desired radiation patterns in the far-field. The OPAs are numerically optimized to have an upward efficiency of up to 90%, targeting radiation concentration mainly in the field of view. We envision that our OPAs have the ability of generating complex holographic images, rendering them an attractive candidate for a wide range of applications like LiDAR sensors, optical trapping, optogenetic stimulation and augmented-reality displays. author: - first_name: Henna full_name: Farheen, Henna last_name: Farheen - first_name: Andreas full_name: Strauch, Andreas last_name: Strauch - first_name: J. Christoph full_name: Scheytt, J. Christoph id: '37144' last_name: Scheytt orcid: https://orcid.org/0000-0002-5950-6618 - first_name: Viktor full_name: Myroshnychenko, Viktor id: '46371' last_name: Myroshnychenko - first_name: Jens full_name: Förstner, Jens id: '158' last_name: Förstner orcid: 0000-0001-7059-9862 citation: ama: 'Farheen H, Strauch A, Scheytt JC, Myroshnychenko V, Förstner J. Optimized silicon antennas for optical phased arrays. In: García-Blanco SM, Cheben P, eds. Integrated Optics: Devices, Materials, and Technologies XXVII. SPIE; 2023:124241D. doi:10.1117/12.2658716' apa: 'Farheen, H., Strauch, A., Scheytt, J. C., Myroshnychenko, V., & Förstner, J. (2023). Optimized silicon antennas for optical phased arrays. In S. M. García-Blanco & P. Cheben (Eds.), Integrated Optics: Devices, Materials, and Technologies XXVII (p. 124241D). SPIE. https://doi.org/10.1117/12.2658716' bibtex: '@inproceedings{Farheen_Strauch_Scheytt_Myroshnychenko_Förstner_2023, title={Optimized silicon antennas for optical phased arrays}, DOI={10.1117/12.2658716}, booktitle={Integrated Optics: Devices, Materials, and Technologies XXVII}, publisher={SPIE}, author={Farheen, Henna and Strauch, Andreas and Scheytt, J. Christoph and Myroshnychenko, Viktor and Förstner, Jens}, editor={García-Blanco, Sonia M. and Cheben, Pavel}, year={2023}, pages={124241D} }' chicago: 'Farheen, Henna, Andreas Strauch, J. Christoph Scheytt, Viktor Myroshnychenko, and Jens Förstner. “Optimized Silicon Antennas for Optical Phased Arrays.” In Integrated Optics: Devices, Materials, and Technologies XXVII, edited by Sonia M. García-Blanco and Pavel Cheben, 124241D. SPIE, 2023. https://doi.org/10.1117/12.2658716.' ieee: 'H. Farheen, A. Strauch, J. C. Scheytt, V. Myroshnychenko, and J. Förstner, “Optimized silicon antennas for optical phased arrays,” in Integrated Optics: Devices, Materials, and Technologies XXVII, 2023, p. 124241D, doi: 10.1117/12.2658716.' mla: 'Farheen, Henna, et al. “Optimized Silicon Antennas for Optical Phased Arrays.” Integrated Optics: Devices, Materials, and Technologies XXVII, edited by Sonia M. García-Blanco and Pavel Cheben, SPIE, 2023, p. 124241D, doi:10.1117/12.2658716.' short: 'H. Farheen, A. Strauch, J.C. Scheytt, V. Myroshnychenko, J. Förstner, in: S.M. García-Blanco, P. Cheben (Eds.), Integrated Optics: Devices, Materials, and Technologies XXVII, SPIE, 2023, p. 124241D.' date_created: 2023-03-21T12:35:18Z date_updated: 2023-03-22T20:53:50Z ddc: - '530' department: - _id: '61' - _id: '230' - _id: '429' doi: 10.1117/12.2658716 editor: - first_name: Sonia M. full_name: García-Blanco, Sonia M. last_name: García-Blanco - first_name: Pavel full_name: Cheben, Pavel last_name: Cheben file: - access_level: request content_type: application/pdf creator: fossie date_created: 2023-03-22T07:41:49Z date_updated: 2023-03-22T20:53:11Z file_id: '43055' file_name: 2023-01 Poster Photonics West Henna OPA_A0.pdf file_size: 1747396 relation: main_file file_date_updated: 2023-03-22T20:53:11Z has_accepted_license: '1' keyword: - tet_topic_opticalantenna language: - iso: eng page: '124241D ' publication: 'Integrated Optics: Devices, Materials, and Technologies XXVII' publication_status: published publisher: SPIE status: public title: Optimized silicon antennas for optical phased arrays type: conference user_id: '14931' year: '2023' ... --- _id: '43245' abstract: - lang: eng text: High-contrast slab waveguide Bragg gratings with 1D periodicity are investigated. For specific oblique excitation by semi-guided waves at sufficiently high angles of incidence, the idealized structures do not exhibit any radiative losses, such that reflectance and transmittance for the single port mode add strictly up to one. We consider a series of symmetric, fully and partly etched finite gratings, for parameters found in integrated silicon photonics. These can act as spectral filters with a reasonably flattop response. Apodization can lead to more box shaped reflectance and transmittance spectra. Together with a narrowband Fabry–Perot filter, these configurations are characterized by reflection bands, or transmittance peaks, with widths that span three orders of magnitude. author: - first_name: Manfred full_name: Hammer, Manfred id: '48077' last_name: Hammer orcid: 0000-0002-6331-9348 - first_name: Henna full_name: Farheen, Henna last_name: Farheen - first_name: Jens full_name: Förstner, Jens id: '158' last_name: Förstner orcid: 0000-0001-7059-9862 citation: ama: Hammer M, Farheen H, Förstner J. How to suppress radiative losses in high-contrast integrated Bragg gratings. Journal of the Optical Society of America B. 2023;40(4):862. doi:10.1364/josab.485725 apa: Hammer, M., Farheen, H., & Förstner, J. (2023). How to suppress radiative losses in high-contrast integrated Bragg gratings. Journal of the Optical Society of America B, 40(4), 862. https://doi.org/10.1364/josab.485725 bibtex: '@article{Hammer_Farheen_Förstner_2023, title={How to suppress radiative losses in high-contrast integrated Bragg gratings}, volume={40}, DOI={10.1364/josab.485725}, number={4}, journal={Journal of the Optical Society of America B}, publisher={Optica Publishing Group}, author={Hammer, Manfred and Farheen, Henna and Förstner, Jens}, year={2023}, pages={862} }' chicago: 'Hammer, Manfred, Henna Farheen, and Jens Förstner. “How to Suppress Radiative Losses in High-Contrast Integrated Bragg Gratings.” Journal of the Optical Society of America B 40, no. 4 (2023): 862. https://doi.org/10.1364/josab.485725.' ieee: 'M. Hammer, H. Farheen, and J. Förstner, “How to suppress radiative losses in high-contrast integrated Bragg gratings,” Journal of the Optical Society of America B, vol. 40, no. 4, p. 862, 2023, doi: 10.1364/josab.485725.' mla: Hammer, Manfred, et al. “How to Suppress Radiative Losses in High-Contrast Integrated Bragg Gratings.” Journal of the Optical Society of America B, vol. 40, no. 4, Optica Publishing Group, 2023, p. 862, doi:10.1364/josab.485725. short: M. Hammer, H. Farheen, J. Förstner, Journal of the Optical Society of America B 40 (2023) 862. date_created: 2023-03-31T13:04:43Z date_updated: 2023-04-20T10:03:40Z ddc: - '530' department: - _id: '61' - _id: '230' - _id: '429' doi: 10.1364/josab.485725 file: - access_level: open_access content_type: application/pdf creator: fossie date_created: 2023-03-31T13:14:59Z date_updated: 2023-03-31T13:14:59Z file_id: '43247' file_name: ogr-afterreview.pdf file_size: 1982311 relation: main_file file_date_updated: 2023-03-31T13:14:59Z has_accepted_license: '1' intvolume: ' 40' issue: '4' keyword: - tet_topic_waveguide language: - iso: eng oa: '1' page: '862' project: - _id: '53' name: 'TRR 142: TRR 142' - _id: '55' name: 'TRR 142 - B: TRR 142 - Project Area B' - _id: '167' name: 'TRR 142 - B06: TRR 142 - Subproject B06' publication: Journal of the Optical Society of America B publication_identifier: issn: - 0740-3224 - 1520-8540 publication_status: published publisher: Optica Publishing Group status: public title: How to suppress radiative losses in high-contrast integrated Bragg gratings type: journal_article user_id: '158' volume: 40 year: '2023' ...