Distributed amplification for lightwave transmission system
Patent 5058974 Issued on October 22, 1991. Estimated Expiration Date: 
October 6, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
October 6, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesFiber optic amplifier Optical communications system comprising Raman amplification means Fabrication of optical fibers Patent #: 4787927 InventorAssigneeApplicationNo. 418000 filed on 10/06/1989US Classes:385/27, Particular coupling function359/334, Raman or Brillouin process359/341.2, Bi-directional359/341.33, With multiple systems372/6, OPTICAL FIBER LASER385/24Plural (e.g., data bus)ExaminersPrimary: Ullah, Akm E.Attorney, Agent or FirmInternational ClassesG02B 006/26G02B 006/42 AbstractBidirectional lightwave transmission is restored and uniform amplification of lightwave signals over long spans of optical fiber is achieved by employing distributed amplification over the spans. Distributed amplification is achieved with an amplifying optical fiber which includes a long length of optical fiber having a dilute rare-earth dopant concentration substantially in the fiber core region, and a corresponding pump signal generator at at least one end of the doped fiber having the appropriate wavelength and power to cause amplification of optical signals by both Raman effects and stimulated emission from the rare-earth dopants. Dilute concentrations are understood as the range of concentrations substantially satisfying the condition that the gain from the rare-earth dopant, when near saturation, is substantially equal to the fiber loss.Other References
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