128 line photonic switching system using LiNbO3 switch matrices and semiconductor traveling wave amplifiers

The possibility of a 128-line photonic space division switching system incorporating LiNbO₃ switch matrices and semiconductor traveling wave amplifiers (TWAs) is discussed. System design is considered in terms of the most suitable location for the TWA devices that gives the most practical power margin. Design requirements for a 128-line photonic switching system suitable for a small-sized private branch exchange requirement are presented along with experimental results. It has been shown that a five-stage switch cascade, suitable for such a high-capacity switching system with a power margin of greater than 5 dB in the highest switch loss situation is possible, using low-facet-reflection TWAs. Such TWA devices have been developed in the 1.3-μm wavelength region with maximum fiber-to-fiber gain values of 15 dB. With maximum gain-polarization dependencies of 3 dB, switch losses can be compensated even under TM mode operation