Towards multimode optical polymer waveguides with integrated Bragg gratings fabricated by nanoimprinting for load sensor applications

Detection of physical parameters like intensity, wavelength shift, resonance peak bandwidth - key indicators of temperature and strain - is crucial for structural health monitoring particularly in composite materials where early damage detection is vital. This drives interest in optical sensing technologies, such as Bragg grating load sensors in multimode waveguides. We present the fabrication of waveguides and Bragg gratings using a process based on Nanoimprint Lithography (NIL). The waveguides (with a cross-section of 50 × 50μm² and 20 × 20μm²) exhibit high structural quality. Fiber Bragg gratings (FBGs) were incorporated into the waveguides with a period of 800 nm and 290nm. This research aims to develop cost-effective, eco-friendly, and scalable bio- polymer-based solutions for photonic sensors, with potential applications in industrial and environmental monitoring. Future work will explore sustainable, bio-based materials for waveguide fabrication. Optical characterizations and simulations will optimize the Bragg grating design to minimize optical losses and enhance sensitivity.