320-channel multiplexer consisting of 100 GHz-spacedparent AWGand 10 GHz-spaced subsidiary AWGs

Abstract
A 320-channel multiplexer with a channel spacing of 10 GHz in the 1.55 µm wavelength region is reported. This was achieved by using subsidiary 10 GHz-spaced AWGs connected in parallel to a parent 100 GHz-spaced AWG. A pair of input/output ports in every subsidiary AWG were optically connected to the parent AWG. The crosstalk to neighbouring and all other channels was < –20 dB.