Laminated Multilayer Optical Waveguides Enabled by Floating Film Transfer

ABSTRACT A scalable method for fabricating multilayer polymer waveguides consisting of up to three layers two of which are prepared using a floating film transfer technique is presented. As an exemplary polymer material, poly(methyl methacrylate) (PMMA) is selected, a widely used material in polymer waveguide technology. To ensure clean delamination of the PMMA films from the carrier substrate, a surface treatment using a PDAC monolayer that significantly reduces interfacial adhesion, allowing fast and reproducible film transfer is utilized. Key parameters such as immersion angle, speed, and mechanical strain are optimized to prevent transfer defects like wrinkling or cracking of the films. Optical waveguides composed of laminated PMMA layers are then characterized via angular‐resolved transmission spectroscopy and the results are compared to Rigorous Coupled‐Wave Analysis (RCWA) simulations. The stacked waveguides exhibited low extra loss caused by the lamination. Moreover, we demonstrate the fabrication of high‐index‐contrast OrmoStamp/air grating structures integrated within PMMA waveguides. RCWA simulations and spectroscopic measurements show strong agreement. Therefore, this work establishes floating film transfer as a robust, solvent‐free approach for assembling multilayer polymer films, offering design flexibility, compatibility with a wide set of polymer materials, and minimal optical loss.