Fig. 1. (a) Schematic diagram of the proposed graphene-MKR modulator. (b)–(d) Detailed fabrication processes. (e) Optical microscopic image of fabricated graphene-MKR modulator. (f) Raman spectrum of CVD-grown graphene. (g) AFM image. (h) Optical microscope images of MKR illuminated by a red laser and microfiber (inset).

Fig. 2. (a) Experimental setup of phase modulation system based on the graphene-MKR modulator. ASE, amplified spontaneous emission; SMF, single mode fiber; OSA, optical spectrum analyzer. (b) Typical transmission spectrum. (c) Transmission spectra under different voltages. (d) The dependence of spectral shift on voltage and electric power. (e) Thermograms of the graphene-MKR modulator at 0 V (left) and 10 V (right).

Fig. 3. (a) Experimental setup of the optical switch system based on the graphene-MKR modulator. DFB, distributed feedback laser; SMF, single mode fiber. (b)–(d) Waveforms of input voltage (up, blue) and output light (down, black) measured at duty cycle of 50:50, 30:70, and 10:90, respectively. Red lines represent the fitting curves of rising and falling edges of output light waveforms.