▎ 摘　　要

This letter introduces a methyl blue-functionalized reduced graphene oxide (MB-rGO) deposited on a microfiber (MF) and demonstrates its absorption characteristics can be tuned by violet light illumination. MB-rGO is fabricated by rGO stacked to noncovalent MB, exhibiting intriguing optical, electrical properties, and soluble in water. The MB-rGO was utilized as sensitive materials and MF as a substrate. The enhanced interaction between the light and the MB-rGO can be achieved via strong evanescent light of the MF. The experiments show that when the violet light is illuminated onto the MB-rGO film with power ranging from 0.03 to 12.77 mW, the transmitted optical power of the MF changes with a relative variation of 2.5 similar to 3 dB in broadband (1520-1620 nm) operation. The device has a sensitivity of similar to 0.235 dB/mW (1520 nm) and illustrates that the MB-rGO possesses high potentiality in photonic application, such as fiber-optic sensor and other photonic devices.