Effects of rounded corners on the performance of an echelle diffraction grating demultiplexer

The effects of two different types of rounded corner on the performance (such as the insertion loss, the polarization dependent loss (PDL) and the chromatic dispersion) of an echelle diffraction grating (EDG) demultiplexer are analysed by using an accurate method of moment (MoM). The results show that both the insertion loss and the chromatic dispersion increase rapidly as the radius of rounded corners increases. It is shown that the impact of rounded troughs on the PDL is more significant than that of rounded crests. The PDL of an EDG demultiplexer can be reduced near the central wavelength at some special values for the radius of the rounded corners.