Low threshold optical bistability in one-dimensional gratings based on graphene plasmonics

Area of Science:

• Optoelectronics
• Materials Science
• Nonlinear Optics

Background:

• Graphene exhibits unique optical properties due to its electronic band structure.
• Surface plasmon resonance (SPR) in graphene can be tuned by altering the Fermi level.
• Nonlinear optical responses are crucial for developing advanced optical devices.

Purpose of the Study:

• To numerically investigate optical bistability in graphene surface plasmons.
• To explore the tunability and angular dependence of this phenomenon.
• To assess the potential for applications in optical switching.

Main Methods:

• Numerical investigation using grating coupling at normal light incidence.
• Analysis of surface plasmon resonance dependence on graphene's Fermi level.
• Characterization of optical hysteresis, threshold, and response time.

Main Results:

• Observed low-threshold optical hysteresis due to graphene SPR field enhancement and nonlinear response.
• Achieved a threshold of 20 MW/cm² and response time of 1.7 ps.
• Demonstrated angular insensitivity near 15° incident angle.
• Showcased reduced threshold (0.5 MW/cm²) and faster response (800 fs) using graphene nanoribbons.

Conclusions:

• Graphene surface plasmons exhibit tunable optical bistability with potential for low-threshold optical hysteresis.
• The phenomenon is largely insensitive to incident angle, enhancing practical applicability.
• Graphene nanoribbons offer further improvements in threshold and response time for bistable devices and all-optical switching in the mid-IR to THz range.