Design of new family of two-dimensional wavelength-time spreading codes for optical code division multiple access networks

A new two-dimensional code family is proposed for OCDMA networks:having orthogonal properties in both the 'wavelength' and 'time' domains. This code family can be easily constructed from the Hamming correlation concept and dimension expansion, and can also be physically implemented by using an array of Bragg gratings. Numerical simulations and a theoretical analysis demonstrate an improved bit error rate performance with much smaller number of wavelength sets when compared to previous approaches.