Optical spectral-amplitude coder/decoders structured with circulator-free fiber-gratings array

Realization of spectral-amplitude coding (SAC) in a fiber-Bragg-grating (FBG)-based optical code-division multiple-access (OCDMA) network is demonstrated. Based on the developed multiple-access coding techniques, correlation subtractions of nearly orthogonal codes have been applied. We introduce the transmissive spectral characteristics of FBGs to construct our FBG encoder/decoder. It provides several important advantages. First, the cost is lowered due to our circulator-free architecture. Second, the round-trip time problem is resolved. We can also eliminate the effect of chip power variance. The testbed consists of two active encoders and three decoders. Both matched and unmatched cases are demonstrated. Our measurements verify that our proposed scheme is successful and practicable.