Recent developments in optical fiber communication have further opened the door to cost effective Wavelength Division Operation in metropolitan and access optical networks. To take advantage of the widened transmission window, broadly tunable optical distortionless filters must be developed to multiplex and demultiplex optical channels. Tunable optical filters are widely needed to manage channels at the optical layer in DWDM systems. One of the few technologies capable of such a large tuning range is liquid crystal (LC). The large anisotropy and low operational voltage make it an ideal candidate for low cost tunable optical filters. The objective of this book is to discuss flat-top/distortionless tunable filters that provide the channel shape requirements for DWDM systems channels management. This book discuses two novel types of LC based tunable filters; the tunable LC coupled Fabry- Perot filters (TLCCFP-F) and the LC tunable optical interleavers. Although many studies of the tunable LC Fabry-Perot filters have been presented using different configurations, these efforts fail to address the requisite channel shape requirements for distortionless transmission.