Measurement of refractive index profile of non-symmetric, complex silica preforms with high refractive index differences

Jana Probostova; Jiri Slanicka; Jan Mrazek; Ondrej Podrazky; Adam Benda; Pavel Peterka

doi:10.1117/12.2227631

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27 April 2016 Measurement of refractive index profile of non-symmetric, complex silica preforms with high refractive index differences

Jana Probostova, Jiri Slanicka, Jan Mrazek, Ondrej Podrazky, Adam Benda, Pavel Peterka

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Proceedings Volume 9886, Micro-Structured and Specialty Optical Fibres IV; 98861G (2016) https://doi.org/10.1117/12.2227631
Event: SPIE Photonics Europe, 2016, Brussels, Belgium

Abstract

Refractive index profile measurement is a key instrument for characterization of optical properties of preforms, which are used for drawing of high-quality optical fibers. Common industrial optical preform analyzers have been designed for measurement of simple symmetric structures such as step-index or graded-index preforms with refractive index close to the silica (n=1.457 at 633 nm). However, these conditions are usually far from more complex structures used in fiber lasers or in fiber sensor area. Preforms for the drawing of advanced optical fibers, such as Bragg, microstructure or photonic crystal fibers, are usually constituted from stacks with non-symmetric internal structure or composed of alternating layers with high refractive index contrasts. In this paper we present comparison of refractive index profile measurements of simple as well as complex structures with high refractive index differences simulating the Bragg structures. Commercial Photon Kinetics 2600 preform analyzer was used for the refractive index profile measurements. A set of concentrically arranged silica tubes was welded to form a complex preforms. Free space between the tubes was filled by immersion with varying refractive indices to simulate the Bragg structure. Up to three tubes were used for the analysis and the refractive indices of immersion were changed from 1.4 to 1.5. When refractive index of immersion was independently measured the structure of preform was defined. Profiles of these “known” structures were compared to measured data processed by originally proposed algorithm. The work provides an extension of issues of refractive index profile measurements in non-symmetric complex silica structures by a commercial preform analyzer and proposes more convenient methods of numeric data processing.

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Jana Probostova, Jiri Slanicka, Jan Mrazek, Ondrej Podrazky, Adam Benda, and Pavel Peterka "Measurement of refractive index profile of non-symmetric, complex silica preforms with high refractive index differences", Proc. SPIE 9886, Micro-Structured and Specialty Optical Fibres IV, 98861G (27 April 2016); https://doi.org/10.1117/12.2227631

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