Abstract: A modal-domain optical fiber sensor device having the sensing fiber constructed of multimode optical fiber, reflectively terminated on one end, the non-terminated end receiving coherent light and outputting speckle pattern light that is geometrically filtered by at least one detection fibers' diameter, angular position, or physical location in relation to the sensing fiber's non-terminated end. The coherent light is directed from a coherent source to the sensing fiber's non-terminated end by at least one injection optical fiber that is oriented side by side with the detection fibers, and secured within a launch optical coupler (LOC). The LOC secures the non-terminated end of the sensing in light communication with the detection optical fibers and injection optical fibers.