Multimode optical fiber

• US 4,033,667 A
• Filed: 09/12/1975
• Issued: 07/05/1977
• Est. Priority Date: 09/12/1975
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Fleming, James William Jr.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Hille, Rolf
• Application Number:
  US05/612,626
• Time in Patent Office: 662 Days
• Field of Search: 350/96 WG, 350/96 B, 350/96 R, 350/96 GN, 350/175 GN, 106/54, 106/50
• US Class Current: 385/124
• CPC Class Codes: C03B 2201/10 doped with boron C03B2201/14 takes precedence
• CPC Class Codes: C03B 2201/28 doped with phosphorus
• CPC Class Codes: C03B 2203/26 Parabolic or graded index [GRIN] core profile
• CPC Class Codes: C03B 37/01807 Reactant delivery systems, e.g. reactant deposition burners
• CPC Class Codes: C03C 13/045 Silica-containing oxide glass compositions
• CPC Class Codes: C03C 13/046 Multicomponent glass compositions
• CPC Class Codes: G02B 6/02285 Characterised by the polarisation mode dispersion [PMD] properties, e.g. for minimising PMD fabrication methods for minimising PMD C03B37/02745
• CPC Class Codes: G02B 6/0288 Multimode fibre, e.g. graded index core for compensating modal dispersion
• CPC Class Codes: G02B 6/03627 arranged - +

Abstract

A multimode optical fiber waveguide with graded refractive index for lessening modal dispersion depends upon simultaneous grading of both P₂ O₅ and B₂ O₃ within an otherwise generally unmodified silica glass. P₂ O₅ is at a maximum in the axial core region, while B₂ O₃ is generally the only modifier in the peripheral core region. The defined profile, which depends critically upon P₂ O₅ content in the axial composition and somewhat less critically upon the B₂ O₃ peripheral composition content, is near optimum from the standpoint of mode dispersion and remains so for the entire useful range of carrier wavelength (generally defined as from 0.5 to 1.1 μm). Numerical aperture for fibers of the invention are typically at a level of 0.3.

Claims

1. Glass transmission line for the transmission of electromagnetic radiation centering about a wavelength within the range of from 0.5 to 2.0 μ

m, said line comprising a core member manifesting a radially decreasing refractive index for said radiation from the axial core composition to the peripheral core composition, together with a cladding about said core, in which the said core consists essentially of SiO₂ and at least two refractive index modifying ingredients, in which the gradient within the said core is due at least in part to a radially increasing concentration of boron oxide, B₂ O₃, to an ultimate peripheral core composition which is essentially borosilicate containing from 10 mole percent B₂ O₃ to 20 mole percent B₂ O₃, the said gradient approximating the form;

##EQU9## in which the n₁ is the index maximum, r is the distance from the fiber axis, a is the core radius, Δ

is the relative index difference between core center and cladding and α

is a power law exponent which characterizes the profile, characterized in that the said gradient is due, at least in part, to a radially decreasing concentration of phosphorous pentoxide, P₂ O₅, from an axial core composition containing from 10 mole percent P₂ O₅ to 15 mole percent.

2. Line of claim 1 in which the axial core composition consists essentially of phosphosilicate glass and in which the peripheral core composition consists essentially of borosilicate glass.

3. Line of claim 2 in which Δ

in the equation set forth in claim 1 is equal to ##EQU10## n₁ and n₂ are index values as measured in bulk samples of glass of the compositions represented, respectively, by the axial core composition and the peripheral core composition.

4. Line of claim 1 in which α

, the exponent in the equation set forth in claim 1, is equal to approximately 1.9 and in which the electromagnetic radiation centers about a wavelength range of from 0.5 to 1.1 μ

m.