[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - A Demultiplexer Immune from Fabrication-Error Impairments as an Enabler of Compact High-Channel-Count (> 64 ch) Dense WDM Systems on Low-End Si PIC Platforms