Theoretical Investigation of Pulse Temporal Compression by Graphene-Silicon Hybrid Waveguide

By an improved nonlinear Schrödinger optical transmission equation, we theoretically study the pulse evolution dynamics in two-stage temporal compression by a graphene-silicon hybrid waveguide as a phase modulator. Graphene exhibits obvious saturable absorption (SA) but negligible linearly intensity-dependent absorption (IDA) (or two-photon absorption) when the optical intensity in graphene is below the threshold intensity of IDA of graphene. By the utilization of SA and the repression of IDA, for the temporally compressed pulse, the temporal shape can be achieved to be pedestal-free, and the temporal acceleration can be minimized. Meanwhile, the enhancement of linearly intensity-dependent refraction (or Kerr effect) can contribute to the decrement of the size of device and the input power of pulse. This model will be useful to develop graphene-based all-optical modulators in photonic integrated circuits.