Photonic spectral encoder/decoder using an arrayed-waveguide grating for coherent optical code division multiplexing

Code division multiplexing (CDM) is the key technology to realize flexible and dense photonic networks. The variety of codes are very useful for assignment of optical paths, namely, spectral code paths. Efficient spectral encoder and decoder are necessary for such an application. A photonic spectral encoder and decoder pair that uses high-resolution arrayed-waveguide gratings (AWG) is proposed. A reflection-type AWG, which is polarization insensitive and a spatial phase filter on the spectral plane are used. The input pulses are spectrally decomposed to their frequency components. Error-free spectral encoding and decoding of 10 Gbit/s, femtosecond pulses over 40-km transmission fiber was successfully achieved.