We demonstrate the use of deep ultraviolet (DUV) reduction photolithography, today's foremost commercial
nanofabrication technology, in the patterning of integrated nanophotonic filters based on etched channel waveguide
gratings. DUV photolithographic fabrication is seen to enable control over individual grating lines at the level of
nanometers enabling spectral engineering of the filter function in unprecedented fashion. Novel filter apodization
approaches are introduced and demonstrated that uniquely leverage DUV nanofabrication power. The demonstrated
filter functions are highly relevant for coarse wavelength division multiplexing and fiber to the premise applications.