Compared to bipolar sequences, orthogonal quaternary phase sequences are more suitable for optical code devision multiple access (OCDMA) passive optical network (PON) with multi-users for its larger capacity and better cross-correlation character. A orthogonal quaternary phase OCDMA en/decoder based on superstructured fiber Bragg grating is proposed and realized. The proposed en/decoder adopts family A four phase sequences as its address codes and obtain equivalent performance compared to the traditional en-decoder while it needs only one uniform phase board during its fabrication. In order to be compatible to different channels, a novel coding technology is proposed which can encode the user's data with a changed channel. Simulation results show that the en/deconders have higher frequency spectrum efficiency and therefore better en/decoding performance. A 2.5 Gb/s, 156 Gchip/s en-decoding experiment is performed using an en-decoder with its code length 63 and length 4.1 cm, and good en/deconding results are achieved.