Abstract:In this paper, we have briefly review the developing history and recent advances made with regard to helical long-period fiber gratings (HLPGs) in three aspects, i.e., the mode-coupling
Abstract and Figures Long-period fiber gratings (LPFGs) functioning as band-reject filters have played a pivotal role in the realm of optical
2. Long period gratings: a view back Long Period Gratings are a periodic perturbation of the properties of the optical fiber, generally of the refractive index of the core and/or geometry, in a single mode fiber.
Fiber Bragg grating technology is popularly used in measurements of various physical parameters, such as pressure, temperature, and strain for civil
A compact helicoidal long-period fiber grating (HLPFG) was fabricated by twisting a single mode fiber with CO 2 laser beam exposure and its characteristic was experimentally investigated.
In this study, the underlying mechanism for mode coupling and propagation in a strongly-coupled few-period long-period fiber grating (LPG) is firstly revealed both theoretically and
A novel theory, namely, Fourier mode coupling (FMC) theory for long-period fiber gratings (LPFGs) is proposed in this paper.
We study the design of such mode scramblers implemented as long-period multimode fiber gratings for systems using D = 12 modes (six spatial modes). By optimizing the grating chirp
Experimental investigation of the cladding modes excited by long-period gratings, as well as sensitivity of the long-period grating spectrum to
Based on the coupled-mode theory, the coupling mechanism of cascaded long-and short-period gratings (CLBGs) is analyzed, and the reflection spectrum with two reflection peaks resulting
A long-period fiber grating (LPFG) formed in a single-mode fiber is considered as an effective device to tap light from the core of fiber. This light-tapping property of the LPFG allows a
The analytical solution to three-mode coupling equations is presented for the first time. A 3 × 3 transmission matrix is attained and can be used to calculate the transmission spectra of
Decades have passed since the first demonstration of a long-period fiber grating (LPFG) and its practical application for sensors, and, in this period, manufacturing techniques, sensitivity
It offers a concise overview of coupled-mode theory, the fabrication processes, the merits, and the limitations associated with mechanically induced
A long-period fiber grating couples light from a guided mode into forward propagating cladding modes where it is lost due to absorption and scattering. The coupling from the guided mode to cladding
In this paper, we rigorously deduce the coupled-mode equations of a long-period fiber grating and fiber Bragg grating in their cascaded structure (CLBG), based on coupled-mode theory. Next, through the
Nowadays, a principal application of such band-reject filters in fiber optics is embodied in the optical fiber sensor technology. This manuscript is dedicated to exploring the advancement of
Long-period fiber gratings (LPFGs) exhibit resonances at specific wavelengths as a result of coupling of the core mode to discrete cladding modes and can work as wavelength selective optical filters.
For the sensing application of the LPFGs, the characteristics of gratings on the temperature, strain, bending, torsion, and surrounding refractive index have been summarized. And their applications as
The strain response of a long-period fibre grating arise due to the physical elongation of the fibre, changing the grating pitch and the effective refractive index of the core and cladding due to the
In this paper, we have briefly review the developing history and recent advances made with regard to helical long-period fiber gratings (HLPGs) in three
We demonstrate the fabrication of long-period fiber gratings and helical long-period gratings in specialty fibers using focused carbon dioxide laser. The mode coupling and sensing
The long-period fiber gratings can reduce human involvement in the process and help for improvement in performance and operating costs. Various optical techniques like ellipsometry and
A long period grating (LPG) is a longitudinal periodic optical structure that drives couplings from the fundamental core mode into phase-matched co-propagating cladding modes of an optical
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