RT Journal Article
T1 Dual-polarization interferometric sensing for independent characterization  of surface and bulk layers
A1 Sánchez-Ramírez, Ana
A1 Luque-González, José Manuel
A1 Pérez-Sánchez, Laura
A1 Barrio-Segura, Miguel
A1 López-Arroyo, Érika
A1 Godoy-Rubio, Rafael
A1 Oton, Claudio J.
A1 Wanguemert-Pérez, Juan Gonzalo
A1 Molina-Fernández, Íñigo
K1 Biosensores
K1 Interferómetros de polarización
AB Photonic integrated biosensors are a promising solution for biomarker detection in applications ranging from clinical diagnostics to food quality monitoring. However, their response is not only affected by molecular binding at the sensor surface, but also by bulk refractive index variations, background composition changes and temperature fluctuations. Most reported implementations cannot separate these effects, leading to inaccurate measurements. In this work, we present a fully integrated dual-polarization Mach-Zehnder interferometer with coherent detection, capable of distinguishing refractive index changes occurring at different distances above the waveguide surface, thereby enhancing sensor robustness. This is achieved through two separate measurements, one using the Transverse Electric (TE) mode and the other using the Transverse Magnetic (TM) mode. By exploiting their different evanescent field penetration depths and postprocessing the respective signals, we solve a system of equations to decouple surface and bulk contributions. Beyond refractive index sensing, this method could be extended to estimate additional parameters such as molecular layer thickness or temperature variations. The good agreement between simulation and experimental results confirms that the proposed sensor can effectively differentiate between contributions due to protein adsorption or biorecognition events within the 10 nm layer closest to the surface (surface effects) from bulk refractive index variations (background effects). To the best of our knowledge, this is the first demonstration of spatially resolved refractive index discrimination by an integrated photonic biosensor with coherent interrogation, highlighting its competitiveness against current state-of-the-art solutions.
PB Elsevier
YR 2026
FD 2026
LK https://hdl.handle.net/10630/45446
UL https://hdl.handle.net/10630/45446
LA eng
NO Ana Sánchez-Ramírez, José Manuel Luque-González, Laura Pérez-Sánchez, Miguel Barrio-Segura, Érika López-Arroyo, Rafael Godoy-Rubio, Claudio J. Oton, J.Gonzalo Wangüemert-Pérez, Iñigo Molina-Fernández, Dual-polarization interferometric sensing for independent characterization of surface and bulk layers, Optics & Laser Technology, Volume 198, 2026, 114886, ISSN 0030-3992, https://doi.org/10.1016/j.optlastec.2026.114886.
NO Funding for open access charge: Universidad de Málaga / CBUA
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 27 feb 2026