Comparison of AWGs and Echelle Gratings for Wavelength Division Multiplexing on Silicon-on-Insulator

We compare the performance (insertion loss and crosstalk) of silicon-based arrayed waveguide gratings (AWGs) and echelle gratings for different channel spacings. For high-resolution de/multiplexer (DWDM) applications, AWGs are the better choice, whereas echelle gratings perform well for low-resolution de/multiplexer (CWDM) applications. Alternatively, for low-resolution de/multiplexer applications, the conventional box-shaped silicon AWG can be modified by an S-shaped AWG. We report crosstalk as low as -27 dB for regular AWGs, whereas in the S-shaped AWGs, the crosstalk is better than -19 dB, with an insertion loss below -2 dB. The crosstalk of the echelle gratings varies between -19 and -23 dB, with insertion loss below -2 dB.