Recently, Michelson-Gires-Tournois interferometer (MGTI)-based optical interleavers have gained much attention due to its excellent performance, simple configuration, and great potentials. Optical interleaver extends the lifetime of existing demultiplexer in optical fiber communication systems and networks, and acts as cost-effective driver toward a narrower-channel-spacing (100/50/25/12.5GHz), next generation, ultra-dense multichannel DWDM optical network. The objective of this paper is twofold: (1) provide a technical overview of the numerous existing implementations of optical interleaver, and (2) focus on one type of family of interleavers based on MGTI, which the author originally proposed and developed. Here, we discuss the different proposed variations of this novel interleaver and compare numerical results of their performances in terms of their comparative flattop shapes, optical configurations, and chromatic dispersion performances.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.