Different functionalities for an arrayed waveguide grating (AWG) configuration are described, showing that this widely used device can be designed not only to frequency multiplex/demultiplex optical channels, but also to implement the discrete Fourier transform (DFT) and the discrete fractional Fourier transform (DFrFT) of a signal, in all-optical orthogonal frequency division multiplexing (OFDM) systems. In addition 1XN and NxN phased array switches architectures are presented, as well as a new configuration to perform polarization diversity multiplexing. Finally, a general approach is discussed to design optical modulators for any modulation format, using either phase modulators (PM) or electro-absorption modulators (EAM).