Novel multipassband optical filter using all-fiber Michelson-Gires-Tournois structure

In this letter, we present novel efficient flat-top multipassband filters based on all-fiber Michelson-Gires-Tournois interferometric (MGTI) structures. Experimentally, we realized two MGTI filters with channel spacings of 100 and 50 GHz, respectively. Compared with the bulk-optic MGTI filters, the proposed all-fiber devices have some additional advantages such as fully compatible with fiber system, low insertion loss, and low cost.