PERFORMANCE OF AN 8 x 8 LiNbO3 SWITCH MATRIX AS A GIGAHERTZ SELF-ROUTING SWITCHING NODE Indexing terms: Integrated optics, Optical switching

Introduction: Requirements of the physical layer in a photonic switching network include a high channel bandwidth for the throughput of ultra-high bandwidth signals, fast switching speeds and optical processing of switching control algorithms to remove the speed bottleneck imposed by electronic processing. Integrated-optic waveguide switches offer a channel bandwidth comparable to that of the fibre itself. Recently, complex integrated-optic switching structures, such as Ti : LiNbO3 8 x 8 crossbar switch matrices, have been fabricated." Optical decoding of a self-routing protocol has also recently been reported and discussed. With these advances in channel transparency, switching speed and control processing speed, the bandwidth of the photonic switching network will be comparable to the bandwidth of the fibre-optic network. Understanding the high-speed switching characteristics of integrated-optic switch matrices is necessary to optimise performance of the network. The first demonstration of high-bandwidth transmission (80 ps pulses) through a complex switching structure is reported in this letter. The switching characteristics of an 8 x 8 integrated-optic crossbar switch (Ti: LiNbO3) at gigahertz speed are measured. These characteristics include switching rise and fall times, RF/acousto-optic crosstalk and modulation depth. The performance of the switch matrix as an ultrawide-bandwidth switching medium is demonstrated by routing 80ps pulses at a rate of lOOMbit/s. Routing decisions are based on destination information encoded in the data using 125Gbit/s optical spread-spectrum code sequences. The encoding and decoding of optical CDMA (code division multiple access) chip sequences using all-optical techniques is reported.