EP0509577A1
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An active fiber optical amplifier for a fiber optics telecommunication line
Assignee: Pirelli and C SpA
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Filing: 1992-04-02
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Granted: —
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Expires: 2012-04-02
Abstract
Abstract The optical amplifier (1) comprises two amplifying stages, an upstream amplifying stage (S M ) and a downstream amplifying stage (S V ). The former stage comprises an upstream active fiber (9) doped with a fluorescent dopant and connected serially to the optical fiber line (2), an upstream optical coupler (10) connected serially downstream from the upstream section of active fiber (9), a laser diode (11) for supplying pumping energy towards the upstream active fiber (9) through the coupler (10), said coupler being oriented to cause pump energy travel towards said upstream active fiber (9) in the opposite direction from the predetermined signal direction (S); the latter stage (S V ) comprises a downstream active fiber (3) doped with a fluorescent dopant and connected serially in the optical fiber (2), a downstream optical coupler (4) connected serially in the downstream active fiber (3), a laser diode (5) for supplying pumping energy into the downstream active fiber (3) through the downstream coupler (4), a first optical insulator (7) serially connected upstream of the downstream active fiber (3), a second optical insulator (8) serially connected downstream from the downstream active fiber (3).
Inventors
- 👤 Giorgio Grasso
- 👤 Aldo Righetti
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 18:38
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/05; H01S3/06; H01S3/063; H01S3/067; H01S3/06754; H01S3/06758
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
265 words
An active fiber optical amplifier (1) for a fiber optics telecommunication line (2) through which a signal is caused to pass in a predetermined direction (S), of the type comprising an active fiber doped with a fluorescent dopant and an optical coupler through which pumping luminous energy is fed into the active fiber, characterized in that it comprises an upstream amplifying stage (S M ) and a downstream amplifying stage (S V ), consecutively connected along the line (2) in the direction (S) of the transmission signal, in which the upstream amplifying stage (S M ) comprises an upstream active fiber section (9) doped with a fluorescent dopant and connected serially to the optical fiber line (2), an upstream optical coupler (10) connected serially downstream from the upstream active fiber section (9), means (11,12) for supplying pumping energy towards the upstream active fiber section (9) through the coupler (10), said coupler being oriented to cause pump energy travel towards said upstream active fiber section (9) in the opposite direction from the predetermined signal direction (S), and the downstream amplifying stage (S V ) comprises a downstream active fiber section (3) doped with a fluorescent dopant and connected serially in the optical fiber (2), a downstream optical coupler (4) connected serially to the downstream active fiber section (3), means (5,6) of supplying pumping energy into the downstream active fiber section (3) through the downstream coupler (4), a first optical insulator (7) serially connected upstream of the downstream active fiber section (3), a second optical insulator (8) serially connected downstream from the downstream active fiber section (3).
Claim 2
Dependent Claim
91 words
An optical amplifier according to Claim 1, characterized in that the gain of the upstream active fiber section (9) is less than a predetermined maximum value, such as to make the interferometric noise in the upstream active fiber section (9) negligible, and more than a minimum value, such that the contribution to the overall noise figure of the amplifier (1) from the noise figure of the combined components downstream from the upstream active fiber section (9) is made less than 1/10 the noise figure of the upstream active fiber section (9).
Claim 3
Dependent Claim
35 words
An optical amplifier according to Claim 2, characterized in that the predetermined maximum value is 100 times lower than the geometric mean of the reflectivities upstream and downstream of the upstream active fiber section (9).
Claim 4
Dependent Claim
55 words
An optical amplifier according to Claim 3, characterized in that the predetermined maximum value is 100 times lower than the geometric mean of the reflectivity from Rayleigh's diffusion through the line fiber upstream of the upstream active fiber section (9) and the reflectivity of the first insulator (7) toward the upstream active fiber section (9).
Claim 5
Dependent Claim
27 words
An optical amplifier according to Claim 2, characterized in that the gain of the upstream active fiber (9) is within the range of 8 to 15 dB.
Claim 6
Dependent Claim
47 words
An optical amplifier according to Claim 1, characterized in that the downstream coupler (4) is located upstream of the downstream active fiber (3) and is oriented to cause pump energy travel in the downstream active fiber (3) in the same direction as the predetermined signal direction (S).
Claim 7
Dependent Claim
21 words
An optical amplifier according to Claim 1, characterized in that the core dopant in the active fiber sections (3,9) is erbium.
Claim 8
Dependent Claim
18 words
An optical amplifier according to Claim 1, characterized in that the optical couplers (4,10) are fused fiber couplers.
Claim 9
Dependent Claim
50 words
An optical amplifier according to Claim 1, characterized in that the first optical insulator (7) has, toward the upstream active fiber (9) and at the same wavelength as the telecommunication signal, a reflectivity exceeding the reflectivity from Rayleigh's diffusion through the line fiber (2) by no more than 10 dB.
Claim 10
Independent Claim
195 words
A method for amplifying an optical signal in a fiber optics telecommunication line, through which a signal is caused to pass in a predetermined direction (S), by means of an optical active fiber amplifier (1), characterized in that it comprises the steps of: - amplifying the signal in an upstream amplifying stage (S M ) having an upstream active fiber (9) directly coupled to the telecommunication line, with a gain less than a predetermined maximum value, such as to make the interferometric noise in the upstream active fiber (9) negligible, and more than a minimum value, such that the contribution to the overall noise figure of the amplifier (1) from the noise figure of the combined components downstream from the upstream active fiber section (9) is made less than 1/10 the noise figure of the upstream active fiber section (9); and - successively further amplifying the signal in a downstream amplifying stage (S v ), consecutively connected along the line (2) in the direction (S) of the transmission signal, with a gain which is the complement to the desired overall amplifying gain of the amplifier (1), preventing reflections of signal into the downstream amplifying stage.
Claim 11
Dependent Claim
33 words
A method according to Claim 10, characterized in that the predetermined maximum value is 100 times lower than the geometric mean of the reflectivities upstream and downstream of the upstream active fiber (9).
Claim 12
Dependent Claim
55 words
A method according to Claim 10, characterized in that the predetermined maximum value is 100 times lower than the geometric mean of the reflectivity from Rayleigh's diffusion through the line fiber upstream of the upstream active fiber (9) and the reflectivity of the downstream amplifying stage (S v ) toward the upstream active fiber (9).
References Cited (Backward Citations)
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