Second-harmonic generation in nonlinear plasmonic lattices enhanced by quantum emitter gain medium

Area of Science:

• Optics and Photonics
• Quantum Optics
• Materials Science

Background:

• Second-harmonic generation (SHG) is a key nonlinear optical process.
• Plasmonic nanostructures offer unique light-matter interaction properties.
• Quantum emitters (QEs) can modify optical responses.

Purpose of the Study:

• To theoretically investigate SHG in plasmonic nanostructures coupled with QEs.
• To explore enhancement mechanisms for SHG via polariton gain.
• To analyze the role of resonance and local electric fields.

Main Methods:

• Generalization of the driven-dissipative Tavis-Cummings model.
• Inclusion of anharmonic surface plasmon-polariton (SPP) modes.
• Time-domain numerical simulations using a vectorial nonlinear hydrodynamic model coupled with Maxwell-Bloch equations.

Main Results:

• Orders of magnitude enhancement in SHG efficiency due to polariton gain.
• Significant SHG increase when QEs are in resonance with lattice plasmon modes and population inversion is achieved.
• Further enhancement by tuning QEs to localized plasmon modes and leveraging strong local electric fields.

Conclusions:

• Polariton gain is a powerful mechanism for enhancing SHG in plasmonic systems.
• Resonance tuning and incoherent pumping of QEs are crucial for maximizing SHG.
• The study provides a theoretical framework for designing nanostructures with enhanced nonlinear optical properties.