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.

Single-mode-fiber refractive-index profile measurement by reflection method

Abstract: A new technique for measuring the refractive index profile of single-mode fibers based on the reflection method is described, and experimental results are demonstrated. When the core radius of a test fiber is only a few times larger than the laser beam spot size, the reflected power distribution does not indicate the refractive index correctly. However, the true index profile can be calculated from the beam spot size and the reflected power distribution with high accuracy: 0.3-microm spatial resolution and 5% relative refractive-index resolution are obtained for practical single-mode fibers.

Optical fiber having negative dispersion and low slope in the erbium amplifier region

Abstract: A optical fiber [30] is disclosed that is suitable for use in a dispersion-compensated, optical communication system [700] that is served by Erbium-doped fiber amplifiers. The fiber has a negative chromatic dispersion that is more negative than -0.8 ps/(nm-km) over the wavelength region 1530 - 1565 nm, and has a dispersion slope that is less than 0.05 ps/(nm2-km). This fiber exhibits an average optical transmission loss that is less than 0.21 dB/km; and its effective area exceeds 50 µm2, which renders it relatively insensitive to bending loss. The optical fiber includes a core [31] of germanium-doped silica whose refractive index is n1 , and a layer of cladding material [34] that surrounds the core. The cladding comprises approximately pure silica, whose refractive index is n2 . Between the core and the cladding, the fiber further includes first and second annular rings of doped silica. The first annular ring [32] has a width of 4.5 ±1.5 microns, is doped with fluorine, and has a refractive index n3 . The second annular ring [33] is doped with germanium and has a refractive index n4 . These indexes are constrained by the following equations: 0.45 < (n1 - n2 )/n2 < 0.58; -0.09 < (n3 - n2 )/n2 < -0.05; and 0.02 <(n4 - n2 )/n2 < 0.28.

Errors in critical-angle measurement of refractive index of optically absorbing materials

Abstract: Large errors are possible in critical-angle measurements of the refractive index of optical absorbers. These arise from the dependence of the reflectivity and transmissivity of a plane optical interface on the imaginary part of the complex relative refractive index. The errors are calculated directly from the Fresnel equations.

Dispersion-flattened single-mode optical waveguide with large effective mode surface area

Abstract: A single-mode optical waveguide comprises an optical core and a cladding surrounding the optical core having a predetermined refractive index. The core comprises a central area that has a refractive index lower than the predetermined refractive index and annular area around the central area that has a refractive index higher than the predetermined refractive index. Between the peripheral annular area and the cladding is at least one composite annular area made up of two successive annular areas respectively having refractive indices lower than and higher than the predetermined refractive index.

Light control element and light control device

Abstract: A light control element includes a substrate, an optical coupling component formed on the substrate by a photonic crystal structure, and a variable refractive index part provided in a part of the photonic crystal structure so as to divide The optical coupling component into two regions, wherein a traveling direction of a light is changed at an interface of the regions by changing a refractive index at the variable refractive index part such that there is caused a reflection for at least one wavenumber of the light.