▎ 摘　　要

A double D-shaped hole optical fiber coated with graphene is proposed as a polarizer at the wavelength of 1.55 mu m. As the planar surfaces of D-shaped holes are both coated with graphene, the interaction between the core and graphene can be doubled. Moreover, the interaction can be further improved by introducing functional materials into the holes. The proposed fiber provides a high extinction ratio (ER) and low insertion loss, and it operates in the single polarization mode. The ER of 42.5 dB with a 2.5-mm-long optical fiber can be achieved for a transverse-electric-pass polarizer, and the insertion loss is approximately 1.08 dB. Specifically, the proposed fiber can achieve simultaneously dual-band polarization at 1.55 mu m and 1.31 mu m. The proposed fiber is feasible for seamless integration in existing fiber systems. We hope our work benefits high-efficiency polarizers, and we believe that the proposed fiber has some potential applications in photonic integrated circuits. (C) 2018 Optical Society of America.