LOCAL-AREA NETWORK COMMUNICATIONS USING OPTICAL SPREAD-SPECTRUM AND SERIAL-CORRELATION OF BIPOLAR CODES

Three schemes for optical fiber code division multiple access (CDMA) n etworks are presented. These approaches resemble in optics the spread spectrum techniques employed before in radio communications systems. A ll the schemes employ bipolar codes for data encoding and electro-opti c serial correlation for decoding. Use is made of both coherent and di rect detection. The coherent scheme is based on self-homodyning in a n etwork configuration that avoids the requirement for a local oscillato r at each receiver. Incoherent detection is based on a novel encoding format which, when employed along with optical filtering, performs PSK to ASK conversion at the receiver. A high throughput optical network based on random carrier CDMA combined with wavelength division multipl e access is also described. The networks are described conceptually wh ile results of proof-of-principle experiments for the different config urations described are presented. These schemes are more applicable to local area multiple access networks rather than to high-bit-rate syst ems. (C) 1997 Academic Press.