LONG PERIOD GRATINGS IN SEGMENTED CLADDING FIBER

Abstract

Optical fibers are a true representative of the remarkable advancements and speed of adoption and commercialisation of technology in recent decades. Propelled by the invention of the laser in 1960, these tiny waveguides quickly spread from the scientific laboratories into the everyday life: Internet, medical diagnostics, transport, oil and other industries, decoration. For a long period grating (LPG) in segmented cladding fiber (SCF), a periodic modulation of the index of refraction in the fiber core typically has a period in the region from 100 μm to 1000 μm and a length of a few cm [1, 2]. The periodic modulation can be realized by -a permanent modification of the refractive index of the core or by a physical deformation. The transmission spectrum of a typical LPG in SCF consists of a number of rejection bands at resonance wavelengths, each of which corresponds to the coupling between the guided mode and a particular cladding mode. In comparison with fiber Bragg gratings (FBGs), LPGs in SCF offers a number of advantages, including easy fabrication, low insertion loss, and better wavelength tenability. LPGs in SCF have therefore been studied extensively for optical communication and sensing applications...........