Abstract

Generalizing prior results of Henry¹ and Jacobs,² we have shown that the sensitivity of a lightwave system using optical amplifiers both as linear intermediate repeaters and as a receiver preamplifier is given by $\begin{array}{l}{N}_p=\\ 36n_{\text{sp}}\frac{G-1}{G}\left[1+\frac{1}{6}\sqrt{BT+{\left(\frac{N_1}{6n_{\text{sp}}M\left(G-1\right)}\right)}^2}\right]\end{array}$ where N_p is the number of photons per bit to achieve 10⁻⁹ error probability, n_sp(≥1) is the spontaneous emission factor, G is the gain and B is the bandwidth of the amplifier, T is the bit period, M is the number of amplifiers (M − 1 is the number of intermediate repeaters), and N₁ is the number of photons per bit required without amplifiers. (N₁ is a measure of the thermal noise performance of the electrical portion of the receiver. For transimpedance receivers N₁ = 3000. Note that N_p = N₁ for M = 1, G = 1.) The above expression assumes that the gain of each amplifier is the same and compensates for the loss between amplifiers.

© 1991 Optical Society of America