Long-period fiber gratings as band-rejection filters

Investigation of the power coupling of novel wavelength-selective couplers incorporating axially symmetric long-period fibre gratings

“…7,8 It is known that an LPFG structure is a periodic perturbation of the refractive index in a single-mode fibre (SMF), which causes a guided-to-cladding mode power exchange to occur at a certain wavelength. 9 When the forward propagating core mode interacts with the LPFG structure, the guided mode couples to several forward propagating cladding modes. 1,9 In addition to their low back reflection and low insertion loss, LPFGs are easy to fabricate because of a grating period that is normally several hundreds of micrometers.…”

Femtosecond pulse written fiber gratings: a new avenue to integrated fiber technology

“…In this case, the phase difference to be overcome by such gratings is much smaller, thus the period Λ is much larger, typically within the range of a few hundred micrometers. These so-called long period gratings (LPGs) [7,16,17] also have larger bandwidths of the order of 10 nm. Large bandwidths can also be obtained in reflection with a chirped FBG (CFBG).…”

Research Progress of High-Temperature-Resistant Fiber Grating and Application in the Field of Sensing

“…In 1996, AT&T bell laboratories Vengsarkar irradiating hydrogen loaded Silicon germanium fiber by ultraviolet light through amplitude mask, and they produced long period fiber grating (LPFG) for the first time [28]. Then, the domestic and foreign scholars made extensively studied on the production of optical fiber grating, forming a variety of methods, mainly including the preparation method of UV exposure, CO 2 laser preparing method, arc discharge method, corrosion groove preparation method, mechanical micro bending preparation method and the way of ion beam system.…”