Inducing optical self-pulsation by electrically tuning graphene on a silicon microring

Area of Science:

• Photonics and Optoelectronics
• Materials Science
• Nonlinear Optics

Background:

• Graphene's unique optoelectronic properties offer potential for advanced photonic devices.
• Silicon microring resonators are key components in integrated photonics.
• Understanding nonlinear optical effects is crucial for device performance.

Purpose of the Study:

• To investigate the mechanism of self-pulsation in a graphene-on-silicon microring resonator.
• To explore the electrical tunability of graphene's nonlinear optical properties.
• To demonstrate the transition from a stable state to self-pulsation via electrical control.

Main Methods:

• Coupled mode theory framework incorporating nonlinear effects (two-photon absorption, Kerr effect, saturable absorption, free carrier absorption, dispersion).
• Analysis of electrical tunability of absorption and Kerr effect in graphene.
• Numerical simulation of device behavior under constant illumination and varying Fermi levels.

Main Results:

• Identified a self-pulsation mechanism in the graphene-on-silicon microring device.
• Demonstrated electrical switching from a stable state to self-pulsation by tuning graphene's Fermi level.
• Observed a supercritical Hopf bifurcation with a stable 7 GHz pulse frequency and amplitude growth.

Conclusions:

• The graphene-on-silicon microring device exhibits electrically controlled self-pulsation.
• The observed phenomenon is linked to nonlinear optical effects and Hopf bifurcation.
• The CMOS compatibility of graphene facilitates integration with silicon photonic circuits.