[{"author":[{"id":"63231","full_name":"Babel, Silia","orcid":"https://orcid.org/0000-0002-1568-2580","last_name":"Babel","first_name":"Silia"},{"id":"61375","full_name":"Bollmers, Laura","last_name":"Bollmers","first_name":"Laura"},{"first_name":"Franz","last_name":"Roeder","id":"88149","full_name":"Roeder, Franz"},{"first_name":"Werner","id":"63574","full_name":"Ridder, Werner","last_name":"Ridder"},{"last_name":"Golla","full_name":"Golla, Christian","id":"40420","first_name":"Christian"},{"first_name":"Ronja","last_name":"Köthemann","full_name":"Köthemann, Ronja"},{"first_name":"Bernhard","id":"29821","full_name":"Reineke, Bernhard","last_name":"Reineke"},{"last_name":"Herrmann","full_name":"Herrmann, Harald","id":"216","first_name":"Harald"},{"full_name":"Brecht, Benjamin","id":"27150","last_name":"Brecht","orcid":"0000-0003-4140-0556 ","first_name":"Benjamin"},{"first_name":"Christof","last_name":"Eigner","orcid":"https://orcid.org/0000-0002-5693-3083","full_name":"Eigner, Christof","id":"13244"},{"first_name":"Laura","last_name":"Padberg","full_name":"Padberg, Laura","id":"40300"},{"full_name":"Silberhorn, Christine","id":"26263","last_name":"Silberhorn","first_name":"Christine"}],"volume":33,"date_updated":"2026-01-07T11:28:35Z","oa":"1","main_file_link":[{"open_access":"1","url":"https://opg.optica.org/oe/fulltext.cfm?uri=oe-33-25-52729"}],"doi":"10.1364/oe.571605","publication_status":"published","publication_identifier":{"issn":["1094-4087"]},"citation":{"apa":"Babel, S., Bollmers, L., Roeder, F., Ridder, W., Golla, C., Köthemann, R., Reineke, B., Herrmann, H., Brecht, B., Eigner, C., Padberg, L., &#38; Silberhorn, C. (2025). Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths. <i>Optics Express</i>, <i>33</i>(25), Article 52729. <a href=\"https://doi.org/10.1364/oe.571605\">https://doi.org/10.1364/oe.571605</a>","short":"S. Babel, L. Bollmers, F. Roeder, W. Ridder, C. Golla, R. Köthemann, B. Reineke, H. Herrmann, B. Brecht, C. Eigner, L. Padberg, C. Silberhorn, Optics Express 33 (2025).","bibtex":"@article{Babel_Bollmers_Roeder_Ridder_Golla_Köthemann_Reineke_Herrmann_Brecht_Eigner_et al._2025, title={Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths}, volume={33}, DOI={<a href=\"https://doi.org/10.1364/oe.571605\">10.1364/oe.571605</a>}, number={2552729}, journal={Optics Express}, publisher={Optica Publishing Group}, author={Babel, Silia and Bollmers, Laura and Roeder, Franz and Ridder, Werner and Golla, Christian and Köthemann, Ronja and Reineke, Bernhard and Herrmann, Harald and Brecht, Benjamin and Eigner, Christof and et al.}, year={2025} }","mla":"Babel, Silia, et al. “Ultrabright, Two-Color Photon Pair Source Based on Thin-Film Lithium Niobate for Bridging Visible and Telecom Wavelengths.” <i>Optics Express</i>, vol. 33, no. 25, 52729, Optica Publishing Group, 2025, doi:<a href=\"https://doi.org/10.1364/oe.571605\">10.1364/oe.571605</a>.","chicago":"Babel, Silia, Laura Bollmers, Franz Roeder, Werner Ridder, Christian Golla, Ronja Köthemann, Bernhard Reineke, et al. “Ultrabright, Two-Color Photon Pair Source Based on Thin-Film Lithium Niobate for Bridging Visible and Telecom Wavelengths.” <i>Optics Express</i> 33, no. 25 (2025). <a href=\"https://doi.org/10.1364/oe.571605\">https://doi.org/10.1364/oe.571605</a>.","ieee":"S. Babel <i>et al.</i>, “Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths,” <i>Optics Express</i>, vol. 33, no. 25, Art. no. 52729, 2025, doi: <a href=\"https://doi.org/10.1364/oe.571605\">10.1364/oe.571605</a>.","ama":"Babel S, Bollmers L, Roeder F, et al. Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths. <i>Optics Express</i>. 2025;33(25). doi:<a href=\"https://doi.org/10.1364/oe.571605\">10.1364/oe.571605</a>"},"intvolume":"        33","user_id":"63231","department":[{"_id":"288"},{"_id":"623"}],"_id":"63091","article_number":"52729","article_type":"original","type":"journal_article","status":"public","date_created":"2025-12-15T07:20:36Z","publisher":"Optica Publishing Group","title":"Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths","issue":"25","year":"2025","language":[{"iso":"eng"}],"publication":"Optics Express","abstract":[{"lang":"eng","text":"We present the design and characterization of a guided-wave, bright, and highly frequency non-degenerate parametric down-conversion (PDC) source in thin-film lithium niobate. The source generates photon pairs with wavelengths of 815 nm and 1550 nm, linking the visible wavelength regime with telecommunication wavelengths. We confirm the high quality of the generated single photons by determining a value for the heralded second-order correlation function as low as g_h^(2)=(6.7+/-1.1)*10^8-3). Furthermore, we achieve a high spectral brightness of 0.44·10pairs/(smWGHz) which is two orders of magnitude higher than sources based on weakly guiding waveguides. The shape of the PDC spectrum and the strong agreement between the effective and nominal bandwidth highlight our high fabrication quality of periodically poled waveguides. The good agreement between the measured and simulated spectral characteristics of our source demonstrates our excellent understanding of the PDC process. Our result is a valuable step towards practical and scalable quantum communication networks as well as photonic quantum computing."}]},{"status":"public","type":"journal_article","file_date_updated":"2024-06-10T11:25:00Z","department":[{"_id":"61"},{"_id":"429"},{"_id":"623"},{"_id":"263"},{"_id":"288"}],"user_id":"158","_id":"54668","project":[{"grant_number":"231447078","_id":"53","name":"TRR 142: TRR 142 - Maßgeschneiderte nichtlineare Photonik: Von grundlegenden Konzepten zu funktionellen Strukturen"},{"_id":"175","name":"TRR 142 - C11: TRR 142 - Kompakte Photonenpaar-Quelle mit ultraschnellen Modulatoren auf Basis von CMOS und LNOI (C11*)","grant_number":"231447078"},{"_id":"167","name":"TRR 142 - B06: TRR 142 - Ultraschnelle kohärente opto-elektronische Kontrolle eines photonischen Quantensystems (B06*)","grant_number":"231447078"},{"name":"PhoQC: PhoQC: Photonisches Quantencomputing","_id":"266","grant_number":"PROFILNRW-2020-067"}],"intvolume":"        32","page":"22878","citation":{"ama":"Hammer M, Babel S, Farheen H, et al. Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides. <i>Optics Express</i>. 2024;32(13):22878. doi:<a href=\"https://doi.org/10.1364/oe.521766\">10.1364/oe.521766</a>","ieee":"M. Hammer <i>et al.</i>, “Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides,” <i>Optics Express</i>, vol. 32, no. 13, p. 22878, 2024, doi: <a href=\"https://doi.org/10.1364/oe.521766\">10.1364/oe.521766</a>.","chicago":"Hammer, Manfred, Silia Babel, Henna Farheen, Laura Padberg, J. Christoph Scheytt, Christine Silberhorn, and Jens Förstner. “Estimation of Losses Caused by Sidewall Roughness in Thin-Film Lithium Niobate Rib and Strip Waveguides.” <i>Optics Express</i> 32, no. 13 (2024): 22878. <a href=\"https://doi.org/10.1364/oe.521766\">https://doi.org/10.1364/oe.521766</a>.","apa":"Hammer, M., Babel, S., Farheen, H., Padberg, L., Scheytt, J. C., Silberhorn, C., &#38; Förstner, J. (2024). Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides. <i>Optics Express</i>, <i>32</i>(13), 22878. <a href=\"https://doi.org/10.1364/oe.521766\">https://doi.org/10.1364/oe.521766</a>","mla":"Hammer, Manfred, et al. “Estimation of Losses Caused by Sidewall Roughness in Thin-Film Lithium Niobate Rib and Strip Waveguides.” <i>Optics Express</i>, vol. 32, no. 13, Optica Publishing Group, 2024, p. 22878, doi:<a href=\"https://doi.org/10.1364/oe.521766\">10.1364/oe.521766</a>.","short":"M. Hammer, S. Babel, H. Farheen, L. Padberg, J.C. Scheytt, C. Silberhorn, J. Förstner, Optics Express 32 (2024) 22878.","bibtex":"@article{Hammer_Babel_Farheen_Padberg_Scheytt_Silberhorn_Förstner_2024, title={Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides}, volume={32}, DOI={<a href=\"https://doi.org/10.1364/oe.521766\">10.1364/oe.521766</a>}, number={13}, journal={Optics Express}, publisher={Optica Publishing Group}, author={Hammer, Manfred and Babel, Silia and Farheen, Henna and Padberg, Laura and Scheytt, J. Christoph and Silberhorn, Christine and Förstner, Jens}, year={2024}, pages={22878} }"},"publication_identifier":{"issn":["1094-4087"]},"has_accepted_license":"1","publication_status":"published","doi":"10.1364/oe.521766","volume":32,"author":[{"first_name":"Manfred","id":"48077","full_name":"Hammer, Manfred","orcid":"0000-0002-6331-9348","last_name":"Hammer"},{"first_name":"Silia","last_name":"Babel","orcid":"https://orcid.org/0000-0002-1568-2580","id":"63231","full_name":"Babel, Silia"},{"full_name":"Farheen, Henna","id":"53444","orcid":"0000-0001-7730-3489","last_name":"Farheen","first_name":"Henna"},{"first_name":"Laura","last_name":"Padberg","full_name":"Padberg, Laura","id":"40300"},{"first_name":"J. Christoph","id":"37144","full_name":"Scheytt, J. Christoph","orcid":"0000-0002-5950-6618 ","last_name":"Scheytt"},{"first_name":"Christine","last_name":"Silberhorn","id":"26263","full_name":"Silberhorn, Christine"},{"id":"158","full_name":"Förstner, Jens","last_name":"Förstner","orcid":"0000-0001-7059-9862","first_name":"Jens"}],"oa":"1","date_updated":"2024-07-22T07:43:02Z","file":[{"file_id":"54669","access_level":"open_access","file_name":"2024-06 Hammer - Optics Express - Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides.pdf","file_size":4004782,"date_created":"2024-06-10T11:25:00Z","creator":"fossie","date_updated":"2024-06-10T11:25:00Z","relation":"main_file","content_type":"application/pdf"}],"abstract":[{"lang":"eng","text":"Samples of dielectric optical waveguides of rib or strip type in thin-film lithium niobate (TFLN) technology are characterized with respect to their optical loss using the Fabry-Pérot method. Attributing the losses mainly to sidewall roughness, we employ a simple perturbational procedure, based on rigorously computed mode profiles of idealized channels, to estimate the attenuation for waveguides with different cross sections. A single fit parameter suffices for an adequate modelling of the effect of the waveguide geometry on the loss levels."}],"publication":"Optics Express","language":[{"iso":"eng"}],"keyword":["tet_topic_waveguide"],"ddc":["530"],"year":"2024","issue":"13","title":"Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides","date_created":"2024-06-10T11:18:06Z","publisher":"Optica Publishing Group"},{"language":[{"iso":"eng"}],"article_number":"23140","keyword":["Atomic and Molecular Physics","and Optics"],"user_id":"63231","department":[{"_id":"15"},{"_id":"230"},{"_id":"623"},{"_id":"288"}],"_id":"45850","status":"public","abstract":[{"text":"Interference between single photons is key for many quantum optics experiments and applications in quantum technologies, such as quantum communication or computation. It is advantageous to operate the systems at telecommunication wavelengths and to integrate the setups for these applications in order to improve stability, compactness and scalability. A new promising material platform for integrated quantum optics is lithium niobate on insulator (LNOI). Here, we realise Hong-Ou-Mandel (HOM) interference between telecom photons from an engineered parametric down-conversion source in an LNOI directional coupler. The coupler has been designed and fabricated in house and provides close to perfect balanced beam splitting. We obtain a raw HOM visibility of (93.5 ± 0.7) %, limited mainly by the source performance and in good agreement with off-chip measurements. This lays the foundation for more sophisticated quantum experiments in LNOI.","lang":"eng"}],"type":"journal_article","publication":"Optics Express","doi":"10.1364/oe.484126","title":"Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler","date_created":"2023-07-03T14:08:36Z","author":[{"orcid":"https://orcid.org/0000-0002-1568-2580","last_name":"Babel","full_name":"Babel, Silia","id":"63231","first_name":"Silia"},{"last_name":"Bollmers","id":"61375","full_name":"Bollmers, Laura","first_name":"Laura"},{"first_name":"Marcello","id":"59545","full_name":"Massaro, Marcello","last_name":"Massaro","orcid":"0000-0002-2539-7652"},{"orcid":"0000-0003-1008-4976","last_name":"Luo","id":"36389","full_name":"Luo, Kai Hong","first_name":"Kai Hong"},{"first_name":"Michael","last_name":"Stefszky","full_name":"Stefszky, Michael","id":"42777"},{"last_name":"Pegoraro","id":"88928","full_name":"Pegoraro, Federico","first_name":"Federico"},{"last_name":"Held","id":"68236","full_name":"Held, Philip","first_name":"Philip"},{"full_name":"Herrmann, Harald","id":"216","last_name":"Herrmann","first_name":"Harald"},{"first_name":"Christof","id":"13244","full_name":"Eigner, Christof","last_name":"Eigner","orcid":"https://orcid.org/0000-0002-5693-3083"},{"first_name":"Benjamin","orcid":"0000-0003-4140-0556 ","last_name":"Brecht","id":"27150","full_name":"Brecht, Benjamin"},{"full_name":"Padberg, Laura","id":"40300","last_name":"Padberg","first_name":"Laura"},{"first_name":"Christine","last_name":"Silberhorn","full_name":"Silberhorn, Christine","id":"26263"}],"volume":31,"publisher":"Optica Publishing Group","date_updated":"2023-07-05T07:58:31Z","citation":{"ama":"Babel S, Bollmers L, Massaro M, et al. Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler. <i>Optics Express</i>. 2023;31(14). doi:<a href=\"https://doi.org/10.1364/oe.484126\">10.1364/oe.484126</a>","ieee":"S. Babel <i>et al.</i>, “Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler,” <i>Optics Express</i>, vol. 31, no. 14, Art. no. 23140, 2023, doi: <a href=\"https://doi.org/10.1364/oe.484126\">10.1364/oe.484126</a>.","chicago":"Babel, Silia, Laura Bollmers, Marcello Massaro, Kai Hong Luo, Michael Stefszky, Federico Pegoraro, Philip Held, et al. “Demonstration of Hong-Ou-Mandel Interference in an LNOI Directional Coupler.” <i>Optics Express</i> 31, no. 14 (2023). <a href=\"https://doi.org/10.1364/oe.484126\">https://doi.org/10.1364/oe.484126</a>.","short":"S. Babel, L. Bollmers, M. Massaro, K.H. Luo, M. Stefszky, F. Pegoraro, P. Held, H. Herrmann, C. Eigner, B. Brecht, L. Padberg, C. Silberhorn, Optics Express 31 (2023).","mla":"Babel, Silia, et al. “Demonstration of Hong-Ou-Mandel Interference in an LNOI Directional Coupler.” <i>Optics Express</i>, vol. 31, no. 14, 23140, Optica Publishing Group, 2023, doi:<a href=\"https://doi.org/10.1364/oe.484126\">10.1364/oe.484126</a>.","bibtex":"@article{Babel_Bollmers_Massaro_Luo_Stefszky_Pegoraro_Held_Herrmann_Eigner_Brecht_et al._2023, title={Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler}, volume={31}, DOI={<a href=\"https://doi.org/10.1364/oe.484126\">10.1364/oe.484126</a>}, number={1423140}, journal={Optics Express}, publisher={Optica Publishing Group}, author={Babel, Silia and Bollmers, Laura and Massaro, Marcello and Luo, Kai Hong and Stefszky, Michael and Pegoraro, Federico and Held, Philip and Herrmann, Harald and Eigner, Christof and Brecht, Benjamin and et al.}, year={2023} }","apa":"Babel, S., Bollmers, L., Massaro, M., Luo, K. H., Stefszky, M., Pegoraro, F., Held, P., Herrmann, H., Eigner, C., Brecht, B., Padberg, L., &#38; Silberhorn, C. (2023). Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler. <i>Optics Express</i>, <i>31</i>(14), Article 23140. <a href=\"https://doi.org/10.1364/oe.484126\">https://doi.org/10.1364/oe.484126</a>"},"intvolume":"        31","year":"2023","issue":"14","publication_status":"published","publication_identifier":{"issn":["1094-4087"]}}]