Optical parametric amplifiers are often used to amplify light with relatively long wavelengths. The accessible wavelength range is usually limited by the transparency range of the nonlinear crystals. If we assume the EDFA gain is homogeneously broadened, the gain of any section the EDFA (along z) can be assumed to have the characteristics below. In long distance undersea and terrestrial point to point links the traffic patterns are relatively. 1- The signal is amplified with gain as in the following equation: ( d I[z ])/(d z) =g I but gain g can be saturated: g= g0/(1+ I(z) /Isat) where g0 is a characteristic value, and Isat, the saturation intensity is: Isat = ( spont/(2 stim)) h n where spont and stim are the. Further, practical issues such as suitable seed sources, gain saturation by pump depletion, and limitations for high-power operation (e., parasitic absorption and gain guiding) are explored. However, unlike fiber based amplifiers such as EDFAs, they suffer from a large noise figure, which severely limits their use for long haul optical communication networks.
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