Design of novel DS-OCDMA encoders/decoders using phase sampled long period grating

A novel long period grating structure with phase sampled technique is proposed to act as encoders/decoders in the direct sequence optical code division multiple access (DS-OCDMA) system. The structure with address code of 31 chips is designed and the relation between the sample period, the input pulse width and the refractive index difference is given. The encoded and decoded results are demonstrated to verify the feasibility of utilizing the coupling ratio to the cladding mode. The whole structure is expected to move on the photonic crystal fiber, for it can support the large refractive index difference between the core mode and cladding mode, as well as minimize the wavelength shift caused by the temperature change.