Graphene-Based D-Shape Twin-Core Fiber Modulator

All-optical modulator based on graphene-photonic crystal fiber

“…raphene has attracted considerable attention in optical devices for its unique structure and excellent optical properties, such as tunable Fermi level, 1,2) ultrafast optical response [3][4][5] and saturation absorption. 6,7) Specifically, the extremely remarkable progress has been made in the graphene-based all-fiber optical devices in the last decade, showing promise in its use in mode-locked lasers 8,9) to optical modulators, [10][11][12] ultrafast detectors, [13][14][15] and fiber sensors. [16][17][18] However, graphene has weak interaction to the perpendicularly incident light (only ∼2.3% optical absorption) because of its single-atom thickness, 19) all optical fibers require special structural treatment, such as fabrication of side-polished fiber 11,20,21) and microfiber 12,[22][23][24] to provide an available platform for twodimensional graphene, in order to achieve light-graphene interaction for monolayer or multi-layer graphene.…”

“…6,7) Specifically, the extremely remarkable progress has been made in the graphene-based all-fiber optical devices in the last decade, showing promise in its use in mode-locked lasers 8,9) to optical modulators, [10][11][12] ultrafast detectors, [13][14][15] and fiber sensors. [16][17][18] However, graphene has weak interaction to the perpendicularly incident light (only ∼2.3% optical absorption) because of its single-atom thickness, 19) all optical fibers require special structural treatment, such as fabrication of side-polished fiber 11,20,21) and microfiber 12,[22][23][24] to provide an available platform for twodimensional graphene, in order to achieve light-graphene interaction for monolayer or multi-layer graphene. Moreover, the inevitable wet-transferring process of graphene greatly limits its optical performance, due to the wrinkles formed and impurities introduced, which further limits the large-size and large-scale applications of graphene.…”

“…Compared to the other methods of fabricating grapheneoptical fiber composite waveguides, it is easier to obtain G-PCF by using direct growing methods without tedious wet transfer processes; this can induce a stronger light-graphene interaction length due to flexible structural characteristics of the PCF. 11,12) Figure 2(a) shows a typical Raman spectrum (HORIBA, XploRA PLUS, 532 nm) of the G-PCF with the APCVD process. The Raman intensity of the 2D band is much stronger than that of the G band with a 2D/G ratio of 1.59, which is characteristic of the monolayer graphene samples.…”