Optical code division multiple access (OCDMA) networks and several typical encoder/decoder (E/D) are introduced. The tunable E/D based on optical fiber delay line (OFDL) and on fiber Bragg gratings (FBGs) have been emphatically investigated. Two schemes of tunable OFDL are presented and their performance is analyzed. The principle of the E/D based on FBGs and the selection of parameters with piezoelectric ceramic (PZT) to tune FBGs are introduced. A two-dimensional tunable structure of E/D based on FBGs arrays are presented, whose merits are analyzed. The construction method of binary phase shift keying (BPSK) and tunable quaternary phase shift keying (QPSK) E/D based on super-structured fiber Bragg grating (SSFBG) are introduced, and the development prospects for OCDMA E/D are analyzed.