Optical fiber for sensors and method for preparation of an optical fiber

摘要

An optical fiber (1) intended to be used as a sensor is of the kind suitable for communication and has a longitudinal cavity or hole (7) which can be intentionally closed or has a more narrow shape at definite positions (8) in the longitudinal direction of the fiber (1). The cavity (7), the diameter of which can be of the magnitude of order of 5 mu m - 50 mu m, is filled with a material changing its volume depending on physical quantities in the fiber environment. The hole (7) can be closed or made narrower at different positions (7) in the longitudinal direction of the fiber for instance by locally heating the fiber by a pulsed laser beam.