van der Waals forces enhanced light–graphene interaction in optical microfiber polarizer

A facile and efficient approach to manufacturing optical devices with a plane graphene-coupled microfiber structure is proposed—attaching the optical microfiber onto a monolayer graphene-coated polydimethylsiloxane substrate. Such devices exhibit strong light–graphene interaction via the evanescent fields of the guided light in microfibers and show evident optical polarization and polarization-dependent saturable absorption effect. When the monolayer graphene with propagation distance is 2.5 mm, and the microfiber diameter is 3.9 μm, the polarization extinction ratio can reach up to 31.0 dB with the light wavelength at 1550 nm. The transmission in TM modes could be increased continuously by increasing the input power of light at 980 nm. The transmission with 3 and 10 dB modulation depths in TM modes could be achieved via 980 nm pump power of 15.1 and 66.1 mW, respectively, which is advantageous over unpolarized graphene-coupled microfiber devices. The proposed microfiber on graphene structure could efficiently integrate optical waveguides with two-dimensional materials, with great potential applications in optical polarizers, all-optical modulators, mode-locked fiber lasers, and sensors, especially for all-fiber systems.