Applications of long-period fiber grating pair interferometers for sensors and communications

Long period fiber grating (LPG) pair interferometers have been widely studied as optical sensor elements and optical communication devices. For optical sensors, they have been employed as bending sensors based on the sensitivity of their interference fringes to the fiber bending and as a measuring tool of the refractive index of the external medium or the induced refractive index in the fiber and so on. For optical communications, these devices have been applied to optical band pass filters or notch filters and used for all-optical signal gating and so on. In this paper we demonstrate that a novel LPG pair interferometer based on the LPG pair between which an erbium-doped fiber (EDF) is inserted can be applied to (a) the optical sensors and (b) optical communications.