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Step-index profile
About: Step-index profile is a research topic. Over the lifetime, 3104 publications have been published within this topic receiving 53199 citations.
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TL;DR: In this paper, the authors evaluate the limitation of the effective area for SM operation by taking into account the effects of practical constraints such as fiber bending loss, laser performance, and fiber mechanical reliability on these LMA fiber designs.
Abstract: Step-index (SI) fiber designs are commonly used in achieving large mode area (LMA) and single-mode (SM) operation in fiber lasers. These fibers can either be intrinsically single-moded fibers or few-moded fibers, which can be forced into SM operation through bending. In this paper we evaluate the limitation of the effective area for SM operation by taking into account the effects of practical constraints such as fiber bending loss, laser performance, and fiber mechanical reliability on these LMA fiber designs. It is shown that the effective area of these fibers cannot be arbitrarily scaled up with the size of the fiber core. We also use the modeling result to provide estimated upper limits to the core diameters and corresponding effective areas for conventional SI fiber designs taking into account fiber parameters that are achievable nowadays.
116 citations
TL;DR: The sensitivity of LPG-based sensors could be enhanced by using a sensing thin film with an allowed large thickness and high refractive index, as demonstrated in this coating schematic.
Abstract: We have theoretically and experimentally demonstrated that the resonant wavelength of long period fiber gratings (LPG) can be shifted by a large magnitude by coating with only a nm-thick thin-film that has a refractive index higher than that of the glass cladding. The resonant wavelength shift can result from either the variation of the thickness of the film and/or the variation of its refractive index. These results demonstrate the sensitivity of LPG-based sensors can be enhanced by using a film of nm-thickness and refractive index greater than silica. This coating schematic offers an efficient platform for achieving high-performance index-modulating fiber devices and high-performance index/thickness-sensing LPG-based fiber sensors for detecting optical property variations of the thin-film coating.
115 citations
TL;DR: Depolarized pump light is used in measurements of the nonlinear refractive index, n2, in optical fiber by the cross-phase-modulation method, and shows that the non linear refractive indices of the optical fibers differ greatly according to glass composition.
Abstract: Depolarized pump light is used in measurements of the nonlinear refractive index, n2, in optical fiber by the cross-phase-modulation method. High measurement repeatability within ±1% is obtained by this method. The nonlinear refractive index is determined for dispersion-shifted fiber, standard single-mode fiber, pure silica-core single-mode fiber, and dispersion-compensating fiber as 3.35 × 10−20, 2.96 × 10−20, 2.79 × 10−20, and 4.44 × 10−20 m2/W, respectively, at 1.55 μm. This shows that the nonlinear refractive indices of the optical fibers differ greatly according to glass composition.
115 citations
TL;DR: Fibers modeled for minimization of modal dispersion having fused silica cores and fluorine doped silica cladding show a strong composition dependence of the optimum refractive index profile.
Abstract: Refractive index dispersion has been determined for fluorine doped fused silica containing 1 and 2% fluorine. Addition of fluorine is found to reduce the refractive index and material dispersion. Fibers modeled for minimization of modal dispersion having fused silica cores and fluorine doped silica cladding show a strong composition dependence of the optimum refractive index profile. Comparison of results with those in the literature based on N.A. vs λ measurements reveal minor discrepancies probably due to the drawing process.
114 citations
TL;DR: In this article, a Mach-Zehnder mode interferometric refractive index sensor was proposed and studied based on splicing points tapered SMF-PCF-SMF (SMF, single-mode fiber; PCF, photonic crystal fiber) structure.
Abstract: The paper proposed and studied a Mach-Zehnder mode interferometric refractive index sensor, which is based on splicing points tapered SMF-PCF-SMF (SMF, single-mode fiber; PCF, photonic crystal fiber) structure. For the reason that the effective refractive index of photonic crystal fiber cladding high-order modes near fiber core are more sensitive to surrounding refractive index changes, the refractive index measurement sensitivity of splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer can be enhanced further through tapering the splicing points. Relations between refractive index measurement sensitivity and photonic crystal fiber length and taper waist diameter are studied through numerical simulations and experiments. Simulation and experimental results show that sensitivity will be increased with the increase of photonic crystal fiber length and the decrease of taper waist diameter. In the refractive range of 1.3333–1.3737, splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm and taper waist diameter of 60.4 μm has refractive index measurement sensitivity of 260.8 nm/RIU, compared with sensitivity of 224.2 nm/RIU of direct splicing SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm, the sensitivity increased by 16.3%. The research shows that the sensing structure is with good linearity and repeatability.
114 citations