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Q: Fachverband Quantenoptik und Photonik
Q 8: Nanophotonics and Integrated Photonics II
Q 8.2: Talk
Monday, March 2, 2026, 17:30–17:45, P 3
On-chip wavefront shaping via transverse mode control in integrated Si3N4 multimode waveguides — •Stefan Rothe, Ekin B. Boşdurmaz, Leonie M. van der Heide, Redlef B. G. Braamhaar, Jeroen P. Korterik, and Pepijn W. H. Pinkse — MESA+ Institute, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
We demonstrate spatial mode control in integrated Si3N4 multimode waveguides (MWGs), establishing a compact and robust platform for wavefront shaping. We fabricate the Si3N4 MWGs on silicon wafers using standard low-loss nanophotonic processes in the MESA+ Nanolab Cleanroom. By adjusting the relative phases of guided transverse modes, we can generate arbitrary output fields like diffraction-limited foci, or any other modal superposition, directly at the chip output facet. One spatial light modulator placed in the conjugate plane of the MWG input enables to coherently excite and control up to five transverse modes. We apply a step-sequential optimization algorithm, and concentrate 76% of the output intensity into a diffraction-limited focus, approaching the π/4-limit for phase-only wavefront shaping. This demonstrates, for the first time, reconfigurable multimode phase control within an integrated Si3N4 platform. Our approach outlines the way for fully integrated spatial light control. Future integration of thermo-optic phase shifters will eliminate bulky free-space optics and enable in-waveguide modulation for scalable multimode quantum networks and photonic computing architectures.
Keywords: Silicon nitride waveguide; Wavefront shaping; Transverse modes; Multimode; quantum computing