Modified legendre sequences for optical CDMA-based passive optical networks

One spectral-amplitude-coding optical code-division multiple access system is presented for passive optical networks. With the cyclic property of arrayed-waveguide grating (AWG) routers and the partially cyclic property of the proposed modified Legendre sequence, the central office needs two AWG routers and one fiber Bragg grating to generate each user's normal and complementary codewords. Thus complementary encoding is accomplished with a cheap and simple configuration, allowing for low-power asynchronous transmission.