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EP0234665A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Fibre-optic coupler

Assignee: Plessey Overseas Ltd
•
Filing: 1987-02-20
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Granted: —
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Expires: 2007-02-20
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Abstract

Abstract A coupler (figure 4) comprising a pair of interwined monomode fibres (41 and 42) optically coupled along a portion of their length. The diameter of one fibre (42) is significantly smaller than that of the other and this fibre (42) is thus wound helically. A helical pitch (Λ) not exceeding 10mm is chosen. For such pitch, the smaller diameter fibre (42) is appreciably longer. The following inequality thus holds:- λ c .L/ΔL ≦ L c : where λ c is the design wavelengt ΔL/L is the difference in fibre lengths per unit length, and L c is the interaction length of the coupler. The signal coupling of the coupler is than a strongly peaked function of wavelength. The coupler is suited to wavelength multiplex/demultiplex applications.

Inventors

  • 👤 William James Stewart

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 03:03
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29331; G02B6/29332; G02B6/2804; G02B6/2821; G02B6/2835

Claims Analysis

Total Claims: 3
Claim 1
Independent Claim 99 words
A fibre-optic coupler (fig. 4) comprising a pair of intertwined monomode fibres (41, 42) optically coupled along a portion (L c ) of their length, the fibres being of different diameter (2a₁, 2a₂); characterised in that the fibre (42) of smaller diameter (2a₂) is helically wound about the other fibre (41) to a fine helical pitch (Λ) such that the following inequality is satisfied:- λ c .L/ΔL ≦ L c ; where λ c is the design waveleng ΔL /L is the difference in fibre lengths per unit length, and L c is the interaction length of the coupler.
Claim 2
Dependent Claim 99 words
A fibre-optic coupler (fig. 4) comprising a pair of intertwined monomode fibres (41, 42) optically coupled along a portion (L c ) of their length, the fibres being of different diameter (2a₁, 2a₂); characterised in that the fibre (42) of smaller diameter (2a₂) is helically wound about the other fibre (41) to a fine helical pitch (Λ) such that the following inequality is satisfied:- λ c .L/ΔL ≦ L c ; where λ c is the design waveleng ΔL /L is the difference in fibre lengths per unit length, and L c is the interaction length of the coupler.
Claim 3
Dependent Claim 32 words
A coupler as claimed in claim 1 wherein the fibre (42) of smaller diameter (2a₂) is a fibre drawn from a fibre nominally identical to the fibre (41) of larger diameter (2a₁).

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