Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Patent
1988-04-25
1989-11-21
Lee, John D.
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
350 9629, 455612, G02B 628
Patent
active
048817902
ABSTRACT:
An optical fiber communications system with Raman amplification of the signal radiation comprises a broadband pump radiation source, or, preferably, a multiplicity of pump radiation sources and polarization maintaining optical fiber as the transmission medium. The sources are selected to result in a pump radiation spectrum having individual spectral components such that pump radiation intensity for each spectral component in the desired polarization in the fiber core is less than a critical intensity I.sub.c. In particular, the average intensity of pump radiation in a first spectral interval, centered on any wavelength .lambda..sub.p in the pump radiation spectrum and of width equal to the Brillouin line width of the fiber at .lambda..sub.p, is to be less than that average intensity in the first spectral interval that results in conversion of 10% of the radiation in the first spectral interval to stimulated Brillouin radiation. Use of a multiplicity of pump sources not only can reduce pump noise and pump depletion due to stimulated Brillouin scattering, but typically also can result in enhanced system reliability and lower cost. In a preferred embodiment, the invention in a soliton fiber communications system, with pump radiation injected at one or more intermediate fiber locations.
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American Telephone and Telegraph Company AT&T Bell Laboratories
Lee John D.
Ranieri Gregory C.
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