EP0441211A2
Expired / Lapsed
EP
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Active fibre optical amplifier, with double-core portions, having a wide signal wavelength band
Assignee: Pirelli and C SpA
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Filing: 1991-01-28
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Granted: —
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Expires: 2011-01-28
Abstract
Abstract The invention relates to an optical amplifier, particularly for optical fibre telecommunications lines, operating with the transmission signal in a predetermined wavelength band, which comprises an active laser emission optical fibre (6), doped with Erbium, having portions (11) of limited length provided with two cores (12, 13), one (12) of which is connected to the cores (16) of the remaining portions of active fibre (6) and with the line fibres (7), constituting the amplifier's input and output, while the second core (13) is optically coupled with the first (12) at a specific wavelength, different from that of transmission; the second core (13) is capable of removing from the first core (12) the spontaneous emission light of the Erbium, which would constitute a source of noise, thus allowing the amplification of a transmission signal in a range of wavelengths substantially corresponding to that of the tolerance of laser signal emitters (2) of a commercial type.
Inventors
- 👤 Giorgo Grasso
- 👤 Paul Laurence Scrivener
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 17:38
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/05; H01S3/06; H01S3/063; H01S3/067; H01S3/06754; G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/2804; G02B6/2821; G02B6/2826; G02B6/283; G02B6/2835; H01S3/06708; G02B2006/2839; H01S2301/00; H01S2301/02; H01S3/06729
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
188 words
Wide signal band optical amplifier, particularly for optical fibre telecommunications lines operating with a transmission signal in a predetermined wavelength band, comprising a dichroic coupler (3), suitable for multiplexing a transmission signal and luminous pumping energy in a single outgoing fibre (4), and an active optical fibre (6) containing a fluorescent dopant, connected to the output fibre (4) of the dichroic coupler (3) and to a telecommunications line fibre (7) suitable for receiving and transmitting an amplified signal, characterised in that the active optical fibre (6) comprises first portions (11), each of which is constituted by an optical fibre having two cores (12, 13), and second portions (15) constituted by an optical fibre having a core (16) containing said fluorescent dopant, the first cores (12) of the first portion being optically connected to the cores (16) of the second portions and the second cores (13) being interrupted at the extremities of the first portions, the two cores (12, 13) being optically coupled together in a wavelength band included in the wavelength range of the laser emission of the first core (12) and different from the transmission signal band.
Claim 2
Dependent Claim
45 words
Wide signal band optical amplifier, according to claim 1, characterized in that the second core (13) of each first portion (11) of the active optical fibre (6) contains a dopant having a high luminous absorption in the laser emission range of the active fibre's dopant.
Claim 3
Dependent Claim
38 words
Wide signal band optical amplifier, according to claim 2, characterized in that the dopant having a high luminous absorption contained in the second core (13) is constituted by the same fluorescent substance present in the active fibre (6).
Claim 4
Dependent Claim
31 words
Wide signal band optical amplifier, according to claim 1, characterized in that the first core (12) of each first portion (11) of the active optical fibre (6) contains a fluorescent dopant.
Claim 5
Dependent Claim
31 words
Wide signal band optical amplifier, according to claim 1, characterized in that the first core (12) of each first portion (11) of the active optical fibre (6) has no fluorescent dopant.
Claim 6
Dependent Claim
34 words
Wide signal band optical amplifier, according to claim 1, characterized in that the fluorescent dopant substance present in the active fibre (6), at least inside its second portions (15) having single core, is Erbium.
Claim 7
Dependent Claim
52 words
Wide signal band optical amplifier, according to claim 2, characterized in that the dopant substance present in the second core (13) is a substance having a high luminous absorption over the entire spectrum, chosen among Titanium, Vanadium, Chromium or Iron, which is present at least in part in their lower valence state.
Claim 8
Dependent Claim
52 words
Wide signal band optical amplifier, according to claim 1, characterized in that the length (L A ) of each first portion (11) is equal to or greater than the beating length (L B ) between the first and second cores (12, 13) thereof coupled in the selected coupling band between the cores.
Claim 9
Dependent Claim
60 words
Wide signal band optical amplifier, according to claim 1, characterized in that the content of dopant having a high luminous absorption of the second core (13) and the coupling characteristics of the fibre cores (12, 13) are correlated so as to determine in the second core a quenching length less than 1/10th of the beating length between the coupled cores.
Claim 10
Dependent Claim
55 words
Wide signal band optical amplifier, according to claim 8, characterized in that the second core (13) has no light absorbing dopant and each two-core fibre portion (11) has a length (L A ) equal to a whole multiple of one beating length (L B ), with a tolerance of 10% of the beating length itself.
Claim 11
Dependent Claim
25 words
Wide signal band optical amplifier, according to claim 6, characterized in that first and second cores are optically coupled together between 1530 and 1540 nm.
Claim 12
Dependent Claim
80 words
Wide signal band optical amplifier, according to claim 1, characterized in that the first core (12) of first portion (11) is arranged coaxially with external surface of the fibre forming the first portion and is in alignment with the cores (16) of said second portions (15) of the active fibre (6) and with the cores of the fibres (7) to which the amplifier is connected, while the second core (13), at its extremities, faces cladding material of the adjacent fibres.
Claim 13
Dependent Claim
42 words
Wide signal band optical amplifier, according to claim 1, characterized in that at least the first (12) of the two cores of the first portions (11) is suitable for allowing monomodal luminous propagation at the transmission wavelength and at the pumping wavelength.
Claim 14
Dependent Claim
61 words
Optical amplifier according to claim 1, characterized in that the active fibre (6) has second portions, containing fluorescent dopant, included between two consecutive double-core first portions (11), having a length (F) not greater than that corresponding to a maximum obtainable gain of 15 dB at the coupling wavelength between the first and second cores (12, 13) of the first portions (11).
Claim 15
Dependent Claim
58 words
Optical amplifier according to claim 14, characterized in that the second portions (15), containing fluorescent dopant, included between two consecutive double-core first portions (11) have a length (F) not greater than that corresponding to a gain between 1 and 5 dB at the coupling wavelength between the first and second cores (12, 13) of the first portions (11).
Claim 16
Dependent Claim
26 words
Optical amplifier according to claim 1, characterized in that at least one extremity of the active fibre (6) is constituted by a double-core first portion (11).
Claim 17
Dependent Claim
32 words
Optical amplifier according to claim 1, characterized in that the double-core first portions (11) are mechanically curvable for fine adjustment of the coupling wavelength band between the first and second cores thereof.
Claim 18
Dependent Claim
28 words
Optical amplifier according to claim 1, characterized in that each double-core first portion (11) is rigidly constrained to a respective support plate (17), substantially undeformable under operational conditions.
Claim 19
Dependent Claim
44 words
Optical amplifier according to claims 17, 18, characterized in that each double-core first portion (11) is rigidly constrained to the respective support plate (17) in a curvature condition corresponding to the desired coupling wavelength band between the first and second cores (12, 13) thereof.
References Cited (Backward Citations)
No citation records indexed.
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