Refractive index dispersion of doped silica for fiber optics

Fiber Optics Research Center, Russian Academy of Sciences, Moskva, Moscow, Russia
Optics Communications (Impact Factor: 1.45). 12/2002; 213(4-6):301-308. DOI: 10.1016/S0030-4018(02)02087-4


The spectral dependencies of refractive index have been measured in Ge-, P-, N-, Cl-, B-, F-, and Al-doped silica glasses as well as in undoped silica glasses using bulk prism samples cut from optical fiber preforms. The latter have been fabricated by MCVD-, PCVD-, and SPCVD-processes. Based on the experimental results, material dispersion in the glasses has been analyzed, which is one of the most important parameters for fiber optics. An assumption has been made regarding the origin of the significant discrepancy of the zero-dispersion wavelength of nominally identical glass compositions in different publications. The effect of chlorine admixture on the dispersion curves has been investigated. Nitrogen-doped silica is shown to be a promising material for broadband graded-index multimode fibers.

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    • "Partly for this reason, the spectral dependence of the refractive index has only been characterized for select dopants at particular concentrations [9] [10] [11] [12] [13]. Furthermore, these studies either required wafer-thin fiber slices [9], which are inherently destructive, expensive to prepare, and permit stress relaxation, or they were performed on homogeneous bulk samples [10] [11] [12] or samples extracted from fiber performs [13], which are poor substitutes for actual fiber samples since they have different thermal histories, minimal dopant diffusion, and have not experienced fiber draw. This paper describes a new, non-destructive, in situ technique for obtaining spectrally resolved refractive index profiles for arbitrary optical fibers across an entire octave with sub-µm spatial resolution in a single measurement. "
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    ABSTRACT: A non-destructive technique to measure an optical fiber's refractive index profile with sub-??m spatial resolution over a wavelength range spanning more than one octave (from 480 to 1040 nm) in a single measurement is described. Data showing the variation of refractive index with wavelength for several fiber types is presented.
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    • "In order to accurately describe the SCF, our model takes into account both the wavelength-dependent refractive indexes of the semiconductor and glass, as well as the index changes in the semiconductor at various carrier concentrations. We assume that both the core and cladding glass layers have the same wavelength-dependent refractive index, with data from [5]. This assumption is valid given the large index difference between semiconductor and glass. "
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