Recent progress on the development of optical fiber sensors for both static and dynamic characterization of new ceramic-matrix composite aerospace structural materials is presented. Optical fiber sensors are employed over electrical strain gage equivalents due primarily to their lower mass, all dielectric construction, and ability to survive much higher temperatures than traditional wire-based strain gage instrumentation. In addition, the fiber sensor design ensures that it is shielded from surface shear strains that typically lead to fatigue-induced failure of wire-filament gages exposed to dynamic loading.
We present recent progress on the commercial development of optical fiber strain gages for both static and dynamic applications up to 1650°C. The low mass and all dielectric nature of optical fiber sensors resists debonding in high vibration environments and completely eliminates noise induced by electromagnetic fields. In addition, the fiber sensor design ensures that it is shielded from surface shear strains that typically lead to debonding and fracture of wire filament gages exposed to long-term cyclical loading.
Ytterbium (Tb) doped double-cladding fiber (DCF) lasers and amplifiers are being developed for a number of industrial and military applications. There are several key factors for maximizing the output power of these devices. Lambda Istruments is concentrating on two areas: component development and optical fiber development. The component development effort has focused on grating devices and pump couplers. Stable, highly reflective short-period fiber Bragg gratings are produced in DCF rapidly, have low insertion loss and can be customized for many different laser/amplifier applications. Long-period gratings are also being developed for possible novel use in fiber laser and amplifier applications. A proprietary fiber coupler under development is currently capable of an 85% coupling efficiency. The second focus for Lambda is the development of polarization maintaining Yb-doped DCF. Recent efforts have shifted towards making large mode area versions of these fibers to reduce nonlinear effects at high powers.
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