Compact bi-directional optical CDMA encoder/decoder with low power dissipation

One decoding structure with power saving ability is proposed for spectral-amplitude-coding (SAC) optical code-division multiple access (OCDMA) system. This decoding structure can avoid unnecessary power loss in the decoder based on fiber Bragg gratings, thus thermal noise in the photodiodes of the decoder is suppressed. In addition, this decoding structure can cooperate with the encoding structure based on arrayed-waveguide grating (AWG) routers with power saving ability to enhance the system performance. Code families generated from cyclic difference sets (CDSs) can be used in this encoding/decoding pair based on AWG routers due to their cyclic properties. Therefore network application such as passive optical network can adopt OCDMA with simper coder configuration and accommodate the same number of users with lower source power.