All-serial coding architecture for ultrafast optical code-division multiple-access

In optical code-division multiple-access (CDMA), the coding architecture of optical encoders, affecting the power budget, size, and cost of the system, is another important factor that needs to be considered, besides the correlation properties of those already extensively studied optical codes. In this paper, an all-serial coding architecture is studied and compared with other optical CDMA coding schemes in terms of the power and delay length requirements. The result reveals that the all-serial architecture performs the best and is particularly suitable for waveguide and free-space operation. A free space optical CDMA experiment demonstrating the feasibility of the all-serial architecture using a serial combination of 50/50 beam splitters and retroreflectors at 100Mbit/s with 100 fs laser pulses is reported.