In this research, we present a novel encoding and decoding structure based upon two-code keying for high-rate spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) systems. The OptiSystem (version 13) simulation software is used to measure the bit-error rate (BER) performance for different fiber lengths. The results indicate that the proposed coding structure clearly provides a significant improvement in performance when compared to the prior reported direct detection technique.