Optical amplification using polarization diversity pumping
First Claim
1. An optical amplifier, comprising:
- a pump source operable to generate an output pump beam comprising two polarization modes, the pump source comprising;
an optical source operable to generate an approximately linearly polarized pump beam comprising a primary polarization direction; and
a polarization maintaining fiber coupled to the optical source;
wherein a principal axis of the polarization maintaining fiber is positioned relative to the primary polarization direction of the approximately linearly polarized pump beam to produce the output pump beam comprising two polarization modes; and
an optical coupler operable to couple at least a portion of the output pump beam to a gain medium to facilitate amplification of at least a portion of an optical signal traversing the gain medium.
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Accused Products
Abstract
This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization. Finally, a two-wavelength amplifier for 1310 nm and 1550 nm can be implemented by using a parallel combination of Raman amplifiers with shared pump lasers or by combining Raman amplifiers with erbium-doped fiber amplifiers. Combinations of the above improvements can be used advantageously to meet specifications for broad bandwidth, polarization independence, noise performance and multi-wavelength operation.
173 Citations
81 Claims
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1. An optical amplifier, comprising:
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a pump source operable to generate an output pump beam comprising two polarization modes, the pump source comprising;
an optical source operable to generate an approximately linearly polarized pump beam comprising a primary polarization direction; and
a polarization maintaining fiber coupled to the optical source;
wherein a principal axis of the polarization maintaining fiber is positioned relative to the primary polarization direction of the approximately linearly polarized pump beam to produce the output pump beam comprising two polarization modes; and
an optical coupler operable to couple at least a portion of the output pump beam to a gain medium to facilitate amplification of at least a portion of an optical signal traversing the gain medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 43, 44, 45, 56, 57)
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16. An optical amplifier, comprising:
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a pump source operable to generate an output pump beam comprising two polarization modes, the pump source comprising;
an optical source operable to generate an approximately linearly polarized pump beam comprising a primary polarization direction; and
a polarization maintaining fiber operable to receive the approximately linearly polarized pump beam;
wherein an angle of a principal axis of the polarization maintaining fiber relative to a launch angle of the approximately linearly polarized pump beam is selected to produce the output beam comprising two polarization modes; and
an optical coupler operable to couple at least a portion of the output pump beam to a gain medium to facilitate amplification of at least a portion of an optical signal traversing the gain medium. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An optical amplifier, comprising:
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a pump source operable to generate an output pump beam comprising two polarization modes, the pump source comprising;
an optical source operable to generate a pump beam comprising primarily a first polarization direction; and
a polarization maintaining fiber operable to receive the pump beam comprising primarily the first polarization direction;
wherein a principal axis of the polarization maintaining fiber is positioned relative to the first polarization direction of the pump beam to produce the output pump beam comprising two polarization modes; and
an optical coupler operable to couple at least a portion of the output pump beam to a gain medium to facilitate amplification of at least a portion of an optical signal traversing the gain medium. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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46. A method of amplifying an optical signal, comprising:
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generating an approximately linearly polarized pump beam comprising a primary polarization direction;
introducing the approximately linearly polarized pump beam into a polarization maintaining fiber;
wherein a principal axis of the polarization maintaining fiber is positioned relative to the primary polarization direction of the pump beam to produce an output pump beam comprising two polarization modes; and
coupling at least a portion of the output pump beam to a gain medium carrying an optical signal to facilitate amplification of at least a portion of the optical signal within the gain medium. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55)
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58. A method of generating an optical pump beam, comprising:
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generating an approximately linearly polarized pump beam;
launching the approximately linearly polarized pump beam into a polarization maintaining fiber;
wherein the approximately linearly polarized pump beam is launched at a selected angle with respect to a principal axis of the polarization maintaining fiber to produce an output pump beam comprising two polarization modes; and
coupling at least a portion of the output pump beam to a gain medium carrying an optical signal to facilitate amplification of at least a portion of the optical signal within the gain medium. - View Dependent Claims (59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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70. A method of generating an optical pump beam, comprising:
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generating a pump beam comprising primarily a first polarization direction;
introducing the pump beam into a polarization maintaining fiber comprising a principal axis;
wherein the principal axis of the polarization maintaining fiber is positioned relative to the first polarization direction of the pump beam to produce a beam comprising two polarization modes; and
coupling at least a portion of the output pump beam to a gain medium carrying an optical signal to facilitate amplification of at least a portion of the optical signal within the gain medium. - View Dependent Claims (71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81)
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Specification