▎ 摘　　要

A compact all-optical tunable fiber filter based on a few-mode optical fiber modal interferometer coated with graphene epoxy resin composite material is proposed and experimentally demonstrated. The interferometer is constructed with a 2-cm FMF connected to two single mode fibers. After coating the graphene epoxy resin composite material on the outside of the interferometer, it shows the all-optical wavelength tunability, and experimental results show that the wavelength shift changes quasilinearly with the pump power changing. The wavelength tunable range reaches 5.062 nm with a step of 0.016 nm/mw. It is expected to have practical application in optical communication, fiber sensing, fiber laser and optical spectrum analysis.