Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 29: Poster – Quantum Technologies I

Q 29.21: Poster

Dienstag, 3. März 2026, 17:00–19:00, Philo 2. OG

Characterization of the swelling behavior of hydrogels using a laser-written Mach-Zehnder interferometer — •Johannes Schnegas¹, Karoline Becker², Alexander Szameit², and Udo Kragl^{1, 3} — ¹Institute of Chemistry, University of Rostock, Germany — ²Institute of Physics, University of Rostock, Germany — ³Department Life, Light & Matter, Faculty for Interdisciplinary Research, University of Rostock, Germany

Hydrogels are 3D polymer networks that can absorb water depending on the surrounding media, such as salt concentration or pH. This allows the use of hydrogels as sensor materials. Swelling directly affects the refractive index of the hydrogel. An integrated optical interferometer, such as the Mach-Zehnder interferometer, is an appropriate sensor for investigating swelling-induced refractive index changes. Its chemical sensing capability has been demonstrated in the literature. In this study, a fs-laser-written MZI fabricated in fused silica was used, which is composed of two waveguides combined by evanescent field couplers. One part of each interferometer arm runs close to the glass surface. A sensor area was created by exposing one of these via mechanical polishing, whereas the other interferometer arm served as a reference. A liquid sample applied to the sensor area results in a shifted phase to which the interferometer responds with a change in the output intensity. This study examines the capability of a laser-written Mach-Zehnder interferometer to characterise the swelling behaviour of hydrogels in different surrounding media.

Keywords: Integrated optical interferometer; Mach-Zehnder interferometer; Hydrogel