Fig. 1. Graphene-based DTCF modulator

Fig. 2. Effective refractive index versus chemical potential when r1=r2=3 μm, D=9 μm, and N=2. (a) Real part of effective refractive index in TE mode; (b) imaginary part of effective refractive index in TE mode; (c) real part of effective refractive index in TM mode; (d) imaginary part of effective refractive index in TM mode

Fig. 3. Effect of core radius on modulator performance. (a) Relationship between chemical potential and loss; (b) relationship between coupled output power of two modulation points and transmission distance when r1=2.5 μm, r2=2.8 μm, D=9 μm, and N=2

Fig. 4. Effect of core distance on modulator performance. (a) Relationship between chemical potential and loss; (b) relationship between coupled output power of two modulation points and transmission distance when r1=2.5 μm, r2=2.8 μm, D=9 μm, and N=2

Fig. 5. Effect of number of graphene layers on modulator performance. (a) Relationship between ΔR and chemical potential; (b) relationship between modulator light intensity loss and chemical potential

Fig. 6. Effect of transition layer material on modulator performance. (a) Relationship between ΔR and chemical potential; (b) relationship between light intensity loss and chemical potential

Fig. 7. Two-dimensional simplified diagram of modulator structure. (a) Side view of modulator structure; (b) simplified circuit model of modulator