Graphene has exceptional electronic transport and photonic properties [1, 2] and as a result this ‘wonder material’ is steadily finding wide-ranging applications in optoelectronic technologies. Although in the short time since its discovery much of the focus has been on its use for electrical devices, more recently a number of graphene-based photonic devices have been demonstrated, including graphene polarizers and electro-absorption based modulators [2, 3]. In this paper, we present a high-performance low-loss broadband fibre polarizer. Previous iterations of such a device require that the optical fibre is polished into the core to provide the required strength of interaction between the graphene sheet and the propagating electromagnetic field, see Fig. 1a [3]. The penalty for this extent of polishing is large device loss (20 dB, at 1550 nm [3]), which has prevented this type of polarizer from becoming a major disruptive technology. With this in mind, we present the first steps towards producing a low-loss in-fibre graphene based polarizer by polishing the fibre close to, but not into, the core. Additional cladding between the fibre core and the graphene sheet reduces the propagation losses but, unfortunately, also decreases the polarizer’s extinction ratio. To address this, we spin coat a polyvinyl butyral (PVB) over-layer onto the graphene which as well as acting as a protective layer, also serves to increase its interaction with the electromagnetic field. A cross-section of the device is shown in Fig. 1b.
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