Fig. 1. Scheme of the experimental setup. WDM, wavelength-division multiplexer; GMF, graphene microfiber; C, fiber optical circulator; FBG, fiber Bragg grating; OSA, optical spectral analyzer.

Fig. 2. Schematic of the GMF. (a) Microscope image of the microfiber. (b) Raman spectrum of the graphene. (c) SEM image of the GMF. (d)–(f) Close-up SEM images of the dashed frame area from the GMF shown in (c).

Fig. 3. Modulated signal light as a function of the pump light power for the GMF using microfiber of (a) 2 μm, (b) 4 μm, and (c) 8 μm diameters. (d) Comparison of microfiber (with 2 μm diameter) without graphene coating.

Fig. 4. Illustration of the Brillouin scattering in the fiber as the phontons move (a) backward and (b) forward. (c) Phonon generation in the SBS process of the pump beam. (d) Brillouin scattering of the signal beam on the phonons.

Fig. 5. Decomposition of the signal spectra obtained from the GMF with the microfiber diameters of (a) 2 μm and (b) 4 μm.

Fig. 6. (a) Experimental setup used to measure the guided acoustic-wave Brillouin scattering from the GMF with a 2 μm diameter. (b) Spectra of the backward propagating light from the GMF with a 2 μm diameter under various pump powers. The central wavelength remains at 1064.35 nm.

Fig. 7. Simulated evanescent field distribution in the microfiber with diameters of (a) 0.5 μm, (b) 1 μm, (c) 2 μm, and (d) 4 μm.