Properties of optical switching networks with passive or active space switches

Fibre optical communications switching networks with optical nodes containing optically passive (lithium niobate) or active (indium phosphide) space switches as well as erbium-doped fibre amplifiers are analysed numerically from a power budget point of view. Calculations include spectral gain characteristics and gain saturation in the optical amplifiers caused by accumulated amplified spontaneous emission and optical signals. Active switches require less transmitter optical power than the passive switches for passage through a given number of nodes because of their lower losses. Critical parameters are identified as the loss in the optical node and the saturation output power of the optical amplifiers