US 6,748,136 B2 · Wide band Raman amplifiers

Abstract

The specification describes a distributed Raman amplifier with multiple pump sources for wide band amplification of wavelength division multiplexed (WDM) signals. It was recognized that using multiple pump sources introduces non-linear effects, such as four wave mixing (FWM). These effects are reduced by multiplexing the pump wavelengths in the multiple pump source. It was also recognized that not all of the pump wavelengths over the wavelength spectrum of the pumps contributes to FWM. Thus fewer than all of the pump wavelengths require multiplexing to eliminate FWM in the multiple wavelength pump source. Various approaches are described to ensure that the pump wavelengths do not interact in FWM in the transmission span. The selected individual pump wavelengths may be either time division multiplexed, or frequency modulated.

Claims12

Dependent claims

An optical system using Raman amplification comprising:

a. a length of optical waveguide,
b. lightwave signal means for introducing a lightwave signal into the optical waveguide, the lightwave signal comprising at least three wavelength division multiplexed (WDM) wavelengths,
c. optical pump means for introducing lightwave pump energy into the core of the glass fiber, whereby the lightwave pump energy interacts with the lightwave signal to produce Raman amplification of the lightwave signal, the optical pump means comprising N individual pump sources, where N is at least 3, each operating at a different wavelength,
the invention characterized by means for modulating N pump sources−X pump sources of the N individual pump sources, where X is at least 1 and where the X pump sources are selectively not modulated.

1 more element

Dependencies are inferred from the claim text.

Wide band Raman amplifiers

Life of this patent

Wide band Raman amplifiers

Life of this patent

Abstract

Claims12