Mesoscale Integrated Photonic Systems for Structural Health Monitoring

The structural integrity of safety-critical aerospace and naval structures is of enduring concern to the navy. Intelligent Structural Health Management (ISHM) systems can help prevent structural failure of safety-critical future naval structures that cannot be allowed to fail in service. As part of the diagnostic system for SHM, photonic sensors (especially fiber-optic) have attracted considerable attention in long-term structural health monitoring. Photonic sensors have proven to be very versatile in terms of their ability to measure multiple parameters, and have other attractive properties including: light weight; immunity to EMI; and massive multiplexability of several hundreds of sensors on a single optical fiber. One major problem, however, continues to plague photonic sensors. Optical fibers are fragile especially at connectorization and ingress/egress points, and are subject to rather stringent alignment requirements. Therefore, while optical fiber sensors have performed very well in laboratory settings, their performance on real structures over extended durations remains questionable. Photonics integration is emerging as a key enabling technology to overcome these limitations. In this project, we propose to develop Mesoscale Integrated Photonic Systems (MIPS) aimed at making photonic sensor systems robust enough to be integrated into real structures. This proposal makes a case for mesoscale (between wafer-level PICs and free-space) integration as the enabling technology that can make photonic sensors robust enough for SHM applications. We propose to develop polymer waveguide-based rigid and flexible MIPS and demonstrate their utility in fiber-optic strain sensor demodulation systems and in chemical sensing systems.