Hybrid direct sequence/frequency hopping encoding/decoding for optical CDMA system using FBGs

A hybrid direct sequence/frequency hopping (DS/FH) scheme is proposed for an optical code division multiple access (OCDMA) system. The optical encoder/decoder with prime-hop codes is based on fiber Bragg gratings (FBGs), and double optical hard-limiters are placed on both sides of decoder respectively. With such a design, the OCDMA system has large number of simultaneous user, high power efficiency and low bit error rate (BER). Furthermore, we apply a new method to calculate the precise BER of the system.