Direct Laser Writing of In-Fiber Ring Resonator Acoustic Emission Sensors for Structural Health Monitoring 20-000000919
Abstract
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.In this project, we propose to develop the science and technology needed forfemtosecond direct laser writing (fDLW) of in-fiber ring resonators (IFRR) within the cladding of single- and dual core optical fibers. This will be done using an amplified femtosecond laser system as the source for densification writing within the glass cladding of optical fibers. The proposed IFRR sensors are aimed at making photonic sensor systems robust enough to be integrated into real structures. The first scheme assumes a single optical bus to which are attached ring resonators, and this is applicable to singlecore fibers and will be referred to as single-bus in-fiber ring resonators (SB-IFRR). The second approach bridges the ring resonators between the two cores of a dual core fiber, and will be referred to as dual-bus in-fiber ring resonators (DB-IFRR). Such systems will have the same Q as Bragg-gratings, but within a much smaller footprint similar to 3D printed ring-resonator sensors leading to higher acoustic frequency response. They will also be much more robust than 3D printed sensors as there is no additional complexity arising from coupling of the sensors to ingress and egress fibers. Applications of these sensors to acoustic emission detection will be demonstrated.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2021
- Source ID
- N000142112233
Entities
People
- Sridhar Krishnaswamy
Organizations
- Northwestern University
- Office of Naval Research
- United States Navy