This work will develop and validate a new wavelength swept laser for fiber optic sensing systems (FOSS). Existing FOSS technology uses external cavity tunable lasers, which are assembled from discrete components with precision intracavity laser alignments. This creates cost and complexity, inhibits volume scaling, and inhibits ruggedization. These factors have in turn inhibited widespread commercial adoption of FOSS in avionics applications and precluded embedding this technology into commercial flight vehicles for continuous in-flight structural health monitoring. Praevium will endeavor to solve these problems by building on its prior work done in developing micro-electromechanical systems tunable vertical cavity surface emitting lasers (MEMS-VCSELs) for swept source optical coherence tomography (SSOCT). Although FOSS employs optical frequency domain reflectometry (OFDR), which is similar to SSOCT, the much longer interferometer delays and much lower wavelength sweep rates employed in FOSS require the effects of Brownian motion on the MEMS actuator to be mitigated. In this work, Praevium Research will minimize the effects of Brownian motion through re-design of the MEMS actuator structure. Additionally, Praevium will develop a low weight and power ruggedized butterfly package based on newly emerging electrically pumped MEMS-VCSELs, eliminating costly and bulky components such as the pump laser, isolator, and wavelength division multiplexer needed in commercial optically pumped devices. Praevium will work with subcontractor Sensuron, who has expertise in FOSS to evaluate the newly developed laser. Sensuron will evaluate the Praevium MEMS-VCSEL in various interferometer configurations, and develop high speed data acquisition and computation to integrate the new laser into a fiber bragg grating based sensor measurement. Results will be compared with existing laser sources.
This work will develop a new cost-effective ruggedized laser technology that will accelerate proliferation of optical frequency domain reflectometry (OFDR) fiber optic sensing of physical parameters such as shape, deflection, temperature, and strain. This will impact the structural engineering and testing of cutting-edge structures and vehicles for land, air, water, and space. This laser technology can also be embedded into vehicles for continuous in-flight structural and health monitoring.
This work will create a new 1550nm widely tunable laser source which provides continuous single mode tuning with low size, weight, and power dissipation in an economical package. This source has non-NASA applications in metrology and spectroscopy. Additionally, the technology developed here will enable fiber-optic shape sensing for medical applications.