Tunable third harmonic generation based on high-Q polarization-controlled hybrid phase-change metasurface

Area of Science:

• Nanophotonics and Metasurfaces
• Nonlinear Optics
• Materials Science

Background:

• Dielectric metasurfaces enhance light-matter interactions, with bound states in the continuum (BICs) improving nonlinear harmonic generation.
• Conventional metasurfaces have fixed operating wavelengths post-fabrication, limiting tunability.

Purpose of the Study:

• To demonstrate tunable third harmonic generation (THG) using a hybrid phase-change metasurface.
• To explore the dynamic control of THG wavelengths through material phase transitions and polarization manipulation.

Main Methods:

• Numerical demonstration of a hybrid metasurface integrating dielectric components with Ge2Sb2Te5 (GST).
• Exploitation of two quasi-BICs, selectively excited by light polarization and tunable via GST phase transition.
• Investigation of electromagnetically induced transparency analog for enhanced THG efficiency.

Main Results:

• Achieved tunable THG with significant efficiency enhancement at quasi-BIC wavelengths.
• Demonstrated dynamic wavelength tuning of THG through GST phase transition and pump light polarization.
• Observed a high-Q analog of electromagnetically induced transparency, further boosting THG efficiency.

Conclusions:

• The developed high-Q, polarization-controlled hybrid phase-change metasurface offers dynamic tunability for nonlinear optical devices.
• This approach provides a pathway for advanced tunable nonlinear optical applications.