AWG technologies for dense WDM applications

This paper reviews the recent technologies supporting arrayed waveguide gratings (AWGs) based on planar lightwave circuits. From the practical point of view, I describe new technologies such as an athermalization and the high-contrast waveguide that includes the mode field transfer needed for low connection loss with conventional optical fiber. As AWG applications, I present new types of AWG modules such as a dynamic gain equalizer and a variable optical attenuator (VOA) MUX/DEMUX. Both of these will play an important role for next-generation wavelength-division multiplexing networks.