EP0567941A2
Expired / Lapsed
EP
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Optical power limiting amplifier
Assignee: Pirelli and C SpA
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Filing: 1993-04-23
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Granted: —
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Expires: 2013-04-23
Abstract
Abstract In an optical amplifier, comprising a rare earth doped optical waveguide, in which signals at signal wavelength and pump power at pump wavelength are coupled together, a differential loss inducing means is located in a predetermined position along the length of the waveguide, causing a loss for the signal greater by a predetermined loss amount than the loss for the pump wavelength, said predetermined loss amount and said predetermined loss position being chosen in a mutual relationship to cause an amplification of lower power input signals, in said signal input power range, greater than the amplification of higher power input signals in said range, by an amount causing a substantially constant output power in a dynamic range of input signals greater than 15 dB.
Inventors
- 👤 Richard Ian Laming
- 👤 Machael Nickolaos Zervas
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 18:05
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/05; H01S3/06; H01S3/063; H01S3/067; H01S3/06754; H01S3/06758; H01S3/06779
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
175 words
An optical amplifier, comprising: - a rare earth doped optical waveguide; - signal input means, receiving a signal at signal wavelength, in a signal input power range; - pumping means supplying pump power at pump wavelength; - coupling means for coupling said signals and pump power in the rare earth doped waveguide; - signal output means, emitting output signals amplified at output power by stimulated emission of said rare earth pumped in said waveguide, characterized in that a differential loss inducing means, causing a loss for the signal greater by a predetermined loss amount than the loss for the pump wavelength, is located in a predetermined position along the length of the waveguide, said predetermined loss amount and said predetermined loss position being chosen in a mutual relationship to cause an amplification of lower power input signals, in said signal input power range, greater than the amplification of higher power input signals in said range, by an amount causing a substantially constant output power in a dynamic range of input signals greater than 15 dB.
Claim 2
Dependent Claim
19 words
An optical amplifier according to claim 1, characterized in that the waveguide comprises a rare earth doped optical fibre.
Claim 3
Dependent Claim
16 words
An optical amplifier according to claim 1, characterized in that the waveguide is doped with erbium.
Claim 4
Dependent Claim
19 words
An optical amplifier according to claim 1, characterized in that said predetermined loss amount is greater than 2 dB.
Claim 5
Dependent Claim
19 words
An optical amplifier according to claim 4, characterized in that said predetermined loss amount is greater than 3 dB.
Claim 6
Dependent Claim
35 words
An optical amplifier according to claim 1, characterized in that said predetermined position along the length of the waveguide is a value comprised between 50 and 75% of the total rare earth doped wavelength length.
Claim 7
Dependent Claim
37 words
An optical amplifier according to claim 1, characterized in that said mutual relationship between said predetermined loss amount and said predetermined loss position includes a loss amount increase with increasing of the position value along the waveguide.
Claim 8
Dependent Claim
35 words
An optical amplifier according to claim 1, characterized in that at least part of the pump power is supplied for propagation in the same direction of the signal within the rare earth doped optical waveguide.
Claim 9
Dependent Claim
37 words
An optical amplifier according to claim 1, characterized in that said differential loss inducing means consists in a coil of one or more loops of an optical fiber, having a predetermined radius, optically coupled to said waveguide.
Claim 10
Dependent Claim
41 words
An optical amplifier according to claim 2, characterized in that said differential loss inducing means consists in a coil of one or more loops of an optical fiber, having a predetermined radius, optically coupled to said rare earth doped optical fibre.
Claim 11
Dependent Claim
27 words
An optical amplifier according to claim 10, characterized in that said coil is formed by one or more loops of the same rare earth doped optical fibre.
Claim 12
Dependent Claim
42 words
An optical amplifier according to claim 10, characterized in that said predetermined loop radius is a radius smaller than a radius at which the propagation mode of the signal wavelength within the fiber experiences a loss greater than 0.1 dB per loop.
Claim 13
Dependent Claim
18 words
An optical amplifier according to claim 10, characterized in that said optical fibre is single-mode at pump wavelength.
Claim 14
Dependent Claim
29 words
An optical amplifier according to claim 13, characterized in that said optical fibre has a cut-off wavelength comprised between 800 and 950 nm, and pump wavelength is 980 nm.
Claim 15
Dependent Claim
19 words
An optical amplifier according to claim 1, characterized in that said differential loss inducing means comprises an optical isolator.
Claim 16
Dependent Claim
23 words
An optical amplifier according to claim 1, characterized in that said differential loss inducing means comprises by-pass means effective for the pump wavelength.
Claim 17
Dependent Claim
39 words
An optical amplifier according to claim 1, characterized in that said coupling means for coupling said signals and pump power in the rare earth doped waveguide comprises a wavelength division multiplexer, having an input connected to a pumping source.
Claim 18
Dependent Claim
63 words
An optical amplifier according to claim 17, characterized in that said coupling means for coupling said signals and pump power in the rare earth doped waveguide comprises a wavelength division multiplexer, having a first input connected to a pumping source, a second input connected to a signal source and an output, where signal and pump power are coupled together, connected to said waveguide.
Claim 19
Dependent Claim
58 words
An optical amplifier according to claim 17, characterized in that said coupling means for coupling said signals and pump power in the rare earth doped waveguide comprises a first wavelength division multiplexer, connected to a first end of said waveguide and a second wavelength division multiplexer, connected to a second end of said waveguide for bidirectional pumping thereof.
Claim 20
Dependent Claim
26 words
An optical amplifier according to claim 1, characterized in that the differential loss inducing means is concentrated in less than 10% of the total waveguide length.
Claim 21
Dependent Claim
66 words
An optical amplifier according to claim 1, characterized in that the differential loss inducing means comprises a first differential loss inducing means, located after a first waveguide portion in the signal propagating direction along the waveguide, and a second differential loss inducing means, separed by an intermediate waveguide portion from said first differential loss inducing means, said first differential loss inducing means comprising an optical isolator.
Claim 22
Dependent Claim
29 words
An optical amplifier according to claim 21, characterized in that at least the differential loss amount due to the second differential loss inducing means is higher than 2 dB.
Claim 23
Dependent Claim
28 words
An optical amplifier according to claim 21, characterized in that the length of the first waveguide portion is comprised between 15 and 45% of the total waveguide length.
Claim 24
Dependent Claim
35 words
An optical amplifier according to claim 21, characterized in that the sum of the lengths of the first waveguide portion and of the intermediate waveguide portion is at least 50% of the total waveguide length.
References Cited (Backward Citations)
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