All-optically controlled slow and fast lights in graphene-coated tilted fiber Bragg grating

We demonstrate all-optically controlled slow and fast lights in tilted fiber Bragg grating (TFBG) with a graphene film. By employing graphene's efficient photothermal effect, the global resonances in TFBG are shifted with slopes of 1.1 and 1.01 pm mW^-1 for cladding and core modes, respectively. This enables changes of group delay and thus supports tunable fast and slow lights from -156 to 20 ps in cladding modes and up to 400 ps in core modes. Our demonstration with an all-in-fiber scheme possesses advantages, such as low-cost manufacture, simple and compact configuration, and multi-wavelength operation.