Local-field-enhanced and polarisation-sensitive graphene/MoS2 film on side-polished fibre with coated Au film

Abstract

The performances of devices based on two-dimensional (2D) materials are limited by their atomic thickness, which leads to ultraweak interactions between light and 2D materials and ultralow optical absorption. We propose an integrated all-fibre platform based on a side-polished fibre (SPF) and graphene/MoS2 (GM) film. A coated Au film can enhance the interaction between the transverse-magnetic-like (TM) mode and GM film owing to the light field confinement effect of the Au film. By coating the Au film, the light absorption by the GM film can be enhanced 4.25 times for the TM mode. Surprisingly, the GM film absorption in the transverse-electric-like (TE) mode is suppressed by the Au film. The coated Au film makes the all-fibre device, based on the GM film, a TE-passing polariser with an extinction ratio of 19.7 dB at 1550 nm, compared to an extinction ratio of 15.9 dB for the Au-film-coated SPF without GM film. The extinction ratio of the all-fibre device can be further increased by reducing the thickness of the Au film. These findings improve our understanding of the interaction between light and 2D materials and provide an effective method towards the development of polarisation-sensitive multi-functional all-fibre devices based on 2D materials.