--- _id: '38051' abstract: - lang: eng text: The characterisation of loss in optical waveguides is essential in understanding the performance of these devices and their limitations. Whilst interferometric-based methods generally provide the best results for low-loss waveguides, they are almost exclusively used to provide characterization in cases where the waveguide is spatially single-mode. Here, we introduce a Fabry-Pérot-based scheme to estimate the losses of a nonlinear (birefringent or quasi-phase matched) waveguide at a wavelength where it is multi-mode. The method involves measuring the generated second harmonic power as the pump wavelength is scanned over the phase matching region. Furthermore, it is shown that this method allows one to infer the losses of different second harmonic spatial modes by scanning the pump field over the separated phase matching spectra. By fitting the measured phase matching spectra from different titanium indiffused lithium niobate waveguides to the model presented in this paper, it is shown that one can estimate the second harmonic losses of a single spatial-mode, at wavelengths where the waveguides are spatially multi-mode. article_number: '5507' author: - first_name: Matteo full_name: Santandrea, Matteo id: '55095' last_name: Santandrea orcid: 0000-0001-5718-358X - first_name: Michael full_name: Stefszky, Michael id: '42777' last_name: Stefszky - first_name: Ganaël full_name: Roeland, Ganaël last_name: Roeland - first_name: Christine full_name: Silberhorn, Christine id: '26263' last_name: Silberhorn citation: ama: Santandrea M, Stefszky M, Roeland G, Silberhorn C. Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation. Optics Express. 2020;28(4). doi:10.1364/oe.380788 apa: Santandrea, M., Stefszky, M., Roeland, G., & Silberhorn, C. (2020). Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation. Optics Express, 28(4), Article 5507. https://doi.org/10.1364/oe.380788 bibtex: '@article{Santandrea_Stefszky_Roeland_Silberhorn_2020, title={Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation.}, volume={28}, DOI={10.1364/oe.380788}, number={45507}, journal={Optics Express}, publisher={Optica Publishing Group}, author={Santandrea, Matteo and Stefszky, Michael and Roeland, Ganaël and Silberhorn, Christine}, year={2020} }' chicago: Santandrea, Matteo, Michael Stefszky, Ganaël Roeland, and Christine Silberhorn. “Interferometric Method for Determining the Losses of Spatially Multi-Mode Nonlinear Waveguides Based on Second Harmonic Generation.” Optics Express 28, no. 4 (2020). https://doi.org/10.1364/oe.380788. ieee: 'M. Santandrea, M. Stefszky, G. Roeland, and C. Silberhorn, “Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation.,” Optics Express, vol. 28, no. 4, Art. no. 5507, 2020, doi: 10.1364/oe.380788.' mla: Santandrea, Matteo, et al. “Interferometric Method for Determining the Losses of Spatially Multi-Mode Nonlinear Waveguides Based on Second Harmonic Generation.” Optics Express, vol. 28, no. 4, 5507, Optica Publishing Group, 2020, doi:10.1364/oe.380788. short: M. Santandrea, M. Stefszky, G. Roeland, C. Silberhorn, Optics Express 28 (2020). date_created: 2023-01-23T09:51:53Z date_updated: 2023-02-01T10:04:19Z department: - _id: '288' doi: 10.1364/oe.380788 intvolume: ' 28' issue: '4' keyword: - Atomic and Molecular Physics - and Optics language: - iso: eng publication: Optics Express publication_identifier: issn: - 1094-4087 publication_status: published publisher: Optica Publishing Group status: public title: Interferometric method for determining the losses of spatially multi-mode nonlinear waveguides based on second harmonic generation. type: journal_article user_id: '42777' volume: 28 year: '2020' ...