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.

High-sensitivity optical fiber refractive index sensor using multimode interference structure

Abstract: This letter presents the experimental investigation to increase the sensitivity of an optical fiber refractive index sensor with a multimode interference (MMI) structure. It is confirmed that the interference wavelength can be set in the long-wavelength region by adjusting the sensing-part length. Moreover, it is shown that the fineness of the cores in the input and output fibers is essential to obtain a sharp interference signal. We demonstrate the high sensitivity of an MMI-structured optical fiber sensor by applying it to refractive index measurements of ethanol/water solutions. This refractive index sensor reveals a resolution as fine as 1.8 × 10-5, which is the highest value so far reported in this type and has one order higher sensitivity than a commercially available Abbe refractometer (∼ 10-4).

Refractive Index Distribution Type Optical Member, and Production Method for Refractive Index Distribution Type Optical Member

Abstract: A graded-index optical member includes a core section which has a maximum portion of a refractive index at a substantial center of a cross-section, and has a refractive index distribution that a refractive index decreases according to distance from the maximum portion. A clad section which contacts at least partially with a periphery of the core section. Refractive index is substantially uniform, by making a concentration distribution of siloxane structure, where concentration increases according to distance from the maximum portion of the refractive index of the core section, formed in a sheet-like polysilane.

Sensitized optical fiber method and article

Abstract: A refractive index grating comprising an optical fiber having at least one radiation-sensitized portion, in a longitudinal section of the optical fiber, containing a periodic variation of refractive index. The refractive index grating has an initial magnitude that changes no more than two percent after conditioning at a temperature of 300° C. for a time of ten minutes.

Optical surface analysis of graded index coatings on glass

Abstract: A method for the determination of the refractive index close to an interface, valid for inhomogeneous films, is presented as an extension of the Abeles—Hacskaylo technique used for homogeneous films. Consistent refractive index values, with precision in the third decimal place, are determined for Ag + (1.550 ± 0.001) and K + (1.522 ± 0.002) ion-exchange films on glass, as well as for bare glass substrates (1.509 ± 0.002), in the neighborhood of their interface with air. The validity of the method is discussed in simple fundamental terms, which, along with the experimental evidences, indicates applicability to any graded index film, provided an index discontinuity is present at one of its extremes.

Low attenuation optical fibers with an F-graded index core

Abstract: An optical fiber is provided that includes a fiber configured to transmit optical data in a plurality of modes or in a single mode; a core region in the fiber that comprises fluorine-doped silica; and a cladding in the fiber that surrounds the core region and that comprises fluorine-doped silica. The core region has a graded refractive index profile with an alpha of about 0.5 to 5. The core of the fiber may be set with a radius of approximately 6 to 50 microns. The cladding may also comprise one or a plurality of layers, including trench or moat regions of a relatively lower refractive index. Still further, an inner cladding may be doped with fluorine at a concentration greater than that in the core region. An outer cladding can comprise silica with fluorine at a concentration below or equal to that in the inner cladding.