Gan Jiajie, Deng Qingyan, Zeng Zijian, Peng Jiantao, Qi Jinlin, Zuo Yonggang, Zhou Xu
Opt Lett. 2024 Oct 1;49(19):5639-5642. doi: 10.1364/OL.534090.
The recent flourishing development of two-dimensional (2D) graphene has sparked considerable interest and extensive research on graphene-based optical fiber polarizers. However, studies on graphene-optical fiber polarizers focused on the structure with graphene films attached to side-polished fibers, which face challenges such as low birefringence of 10, low polarization extinction ratio (PER), and narrow polarizing window of tens of nanometers. Here, a fiber polarizer based on a graphene-photonic crystal fiber (Gr-PCF) is proposed firstly, which exhibits high birefringence of ∼2.5 × 10, high PER of ∼111 dB/mm, broad polarizing window of >400 nm, and tunable polarization states. Graphene or graphene/hBN/graphene (Gr/hBN/Gr) heterojunctions are attached to the surface of two square holes in the PCF to make one of the polarizing modes attenuate significantly. The tunability of the Fermi level (E) in Gr/hBN/Gr enables the proposed device to function as a polarizer or a polarization-maintaining fiber. The combination of PCF's endless single-mode feature and graphene's broadband optical response feature enables the fiber polarizer to exhibit a wide spectrum range with single-mode transmission characteristics.
二维（2D）石墨烯最近蓬勃发展，引发了对基于石墨烯的光纤偏振器的极大兴趣和广泛研究。然而，对石墨烯-光纤偏振器的研究主要集中在石墨烯薄膜附着在侧面抛光光纤上的结构，这种结构面临诸如双折射低至10、偏振消光比（PER）低以及偏振窗口窄至几十纳米等挑战。在此，首次提出了一种基于石墨烯-光子晶体光纤（Gr-PCF）的光纤偏振器，其具有约2.5× 10的高双折射、约111 dB/mm的高PER、大于400 nm的宽偏振窗口以及可调谐偏振态。石墨烯或石墨烯/六方氮化硼/石墨烯（Gr/hBN/Gr）异质结附着在光子晶体光纤中两个方孔的表面，以使其中一个偏振模式显著衰减。Gr/hBN/Gr中费米能级（E）的可调谐性使所提出的器件能够用作偏振器或保偏光纤。光子晶体光纤的无截止单模特性与石墨烯的宽带光学响应特性相结合，使光纤偏振器能够展现出具有单模传输特性的宽光谱范围。
