Thin-film based tunable filter is an ideal candidate for telecom application,especially for DWDM system, on account of its low insertion loss, flat-top transmission spectrum, and excellent thermal stability. With a innovative coating structure to increase the fabrication tolerance at larger AOI and new optical scheme to minimize PDL issue, Lightwaves2020’s step motor controlled 50GHz Angular Tunable Filters (ATF) is a better choice for competitive cost and compact size consideration.