Side-polished evanescently coupled optical fiber overlay devices: a review

Access to the evanescent field of an optical fiber can yield a number of useful optical functions involving coupling of the field to structures formed directly on the fiber. In such devices the fiber remains continuous obviating the need for expensive fiber-to-device interfacing with its requirements for high precision alignment. Continuous fiber devices offer advantages of intrinsically low insertion loss, low back reflections, and excellent mechanical stability relative to their micro-optic or integrated optic counterparts where the fiber needs to be broken for device insertion.