Design of coupled magic angle graphene/single-layer graphene surface-incident 2D photonic modulators

Magic angle graphene is famous for its topological insulator and unconventional superconductivity behavior at cryogenic temperatures. However, few studies have been conducted on its practical applications in other areas, especially in photonics. Here, we design surface-incident 2D material photonic modulators coupling magic angle graphene with monolayer graphene. We calculate the complex refractive index n + ik of the magic angle graphene at different Fermi levels. From the modeling, magic angle graphene behaves in a fashion opposite to single-layer graphene in that its changes from a semimetal to a good metal (n < <k) with external gating. Therefore, this tunable 2D photonic surfaces can provide a unique opportunity in their atomic thickness and a large refractive index change, offering a response time faster than conventional semiconductors. The broadband, angular independent reflection difference between on and off states could reach 70 %, with a low insertion loss of 0.7 dB and a high extinction ratio 6.7 dB, significantly improved from the device with single-layer graphene only (∼0.5 dB insertion loss and 1.7 dB extinction ratio). To our best knowledge, this is the first work to apply the magic angle graphene to 2D photonic devices for optical communications and sensing. • The first exploration of magic-angle graphene (MAG) for photonic device applications at room temperature. • Symmetrically calculating the magic-angle graphene refractive index n and k for different Fermi levels. • Design of MAG/single-layer graphene surface-incident 2D photonic modulators with a high extinction ratio ∼7 dB at a low insertion loss <1 dB. • Unique broad spectral modulation insensitive to incident angles, potentially advantageous over existing surface-incident modulators.