128-LINE PHOTONIC SWITCHING-SYSTEM USING LINBO3 SWITCH MATRICES AND SEMICONDUCTOR TRAVELING-WAVE AMPLIFIERS

This paper discusses the possibility of a 128 line photonic space division switching system incorporating LiNbO3 switch matrices and semiconductor traveling wave amplifiers (TWA's). 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 (PBX) 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 TWA's. Such TWA devices have been developed in the 1.3-mu-m 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.