Optica 1, 307–310 (2014)

Credit: OSA

Wrapping optical microfibre coils around a polymer rod coated with a graphene sheet can yield compact polarizers and high-Q resonators, report scientists from China. Jun-Long Kou and co-workers from Nanjing University say that the approach provides an enhanced and long interaction path between the evanescent light field of the microfibre and the graphene. This interaction can then be exploited for applications such as polarization manipulation or forming a single-polarization resonator. To prevent optical loss from the high-index polymer rod (a piece of PMMA with a diameter of 2 mm) a thin layer of Teflon is applied to the rod's surface prior to application of the graphene sheet, which is made by chemical vapour deposition and then mechanically transferred. Preliminary experiments suggest that a polarizer based on the approach can offer an extinction ratio of 8 dB per each microfibre coil, with a bandwidth of 450 nm in the 1.5 μm telecommunications window. Possibilities for future research include attempting the approach with other two-dimensional materials instead of graphene, such as the transition metal dichalcogenides.