2026-05-30T03:47:41Zhttps://riuma.uma.es/rest/oai/request

oai:riuma.uma.es:10630/403192026-03-13T09:12:08Zcom_10630_2254col_10630_37953

Moreno-Pozas, Laureano Barona-Ruiz, Miguel Halir, Robert De-Oliva-Rubio, José Rivas-Fernández, Jorge Molina-Fernández, Íñigo Wanguemert-Pérez, Juan Gonzalo Ortega-Moñux, Alejandro 2025-10-20T07:20:41Z 2025-10-20T07:20:41Z 2025-02 Moreno-Pozas, L., Barona-Ruiz, M., Halir, R., de-Oliva-Rubio, J., Rivas-Fernández, J., Molina-Fernández, I., ... & Ortega-Moñux, A. (2025). Parabolic dielectric reflector for extreme on-chip spot-size conversion with broad bandwidth. Optics Letters, 50(4), 1073-1076. https://hdl.handle.net/10630/40319 10.1364/OL.546770 Spot-size converters (SSCs) are key for efficient coupling of light between waveguides of different sizes. While adiabatic tapers are well suited for small size differences, they become impractically long for expansion factors around ×100, which are often required when coupling integrated waveguides and free-space beams. Evanescent couplers and Bragg deflectors can be used in this scenario, but their operation is inherently limited in bandwidth. Here, we propose a solution based on a parabolic dielectric interface that couples light from a 0.5um wide waveguide to a 285 um wide waveguide, i.e., an expansion factor of ×570. We experimentally demonstrate an unprecedented bandwidth of more than 380 nm with insertion losses below 0.35 dB. We furthermore provide analytical expressions for the design of such parabolic spot-size converters for arbitrary expansion factors. eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Fotónica Convertidores de frecuencia Difracción Parabolic dielectric reflector for extreme on-chip spot-size conversion with broad bandwidth. journal article