We propose multicavity reflective Gires-Tournois etalons (MCR-GTE) and generalized multicavity transmissive Gires-Tournois etalons (GMCT-GTE) composed of cascaded Sagnac loop mirrors and ring resonators, respectively. Michelson-Gires-Tournois interferometers (MGTI) based on two sets of MCR-GTEs are theoretically studied. As the focal point, we demonstrate the GMCT-GTE, which is a reciprocal and transmissive element as a tunable dispersion compensator (TDC) for the proposed interleaver. The reciprocal and transmissive TDC is superior to reflective ones in terms of saving the number of TDCs. Only one set of TDCs is sufficient for the two output ports of the MGTI proposed. Discussions on fabrication tolerances are given as well, focusing on two main factors that degrade the performance of the interleaver and its TDC in practice, i.e., the length mismatch and loss.