Graphene-Based Floating-Gate Nonvolatile Optical Switch

We proposed a nonvolatile optical waveguide switch by utilizing a floating-gate (FG) configuration whose FG layer is a single-layer graphene. The switching signal can be removed after the optical switching is accomplished. The propagation state of light then can be retained by charges trapped in the graphene layer until the next erasing signal. Depending on waveforms of driving signals, the device can work as either a phase shifter or an intensity switch. In the phase shifter mode, a 646-mu m-long device can achieve a phase shift of pi. Corresponding energy consumptions to program/erase, the pi phase shift is 82.8 and 118.2 pJ, respectively. In the intensity switch mode, a 328-mu m-long device is able to attenuate the light by 20 dB. Energies consumed by the programming and the erasing operations are 35.7 and 45.4 pJ, respectively.