Abstract: The apparatus includes a fiber comprising an axial center, a central single-mode waveguiding core and a plurality of peripheral single-mode waveguiding cores. The central core is located at a first distance from the axial center. The plurality of peripheral cores is located at respective second distances from the axial center. Each of the respective second distances is greater than the first distance, and each peripheral core of the plurality of peripheral cores follows a respective first helix about the axial center. The central core and the plurality of peripheral cores include an optical strain sensor rosette.

Abstract: In accordance with one aspect of the invention, a ring laser configuration having a polarizer, and whose cavity loop has substantially no net dispersion, permitting mode locked pulsing of high intensity and large bandwidth. In accordance with another aspect of the invention, a system using this laser to interrogate a plurality of arrays of Bragg gratings by use of both time and wavelength division multiplexing, increasing the total number of interrogatable gratings. In accordance with a third aspect of the invention, a system for interrogating one or more fiber Bragg gratings separated from the optical source by a dispersive optical fiber. As such a grating distends responsive to some measurand, its reflection frequency changes, and the traversal time of the reflection over the dispersive fiber changes, permitting inference of the measurand.

Abstract: An apparatus for the determination of the wavelength and the detection of velength shifts in wavelength-encoded fiber sensors, such as Bragg grating sensors. The apparatus is implemented in fiber and uses a pair of tuned fiber gratings to provide a filter type function that tracks the wavelength component of a signal from a wavelength-encoded sensor.