Strong second-harmonic response from semiconductor-dielectric interfaces

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Nonlinear optical phenomena like second-harmonic generation (SHG) are crucial for optical technologies.
• Metamaterials offer unique ways to control light-matter interactions through engineered structures.
• Dielectric-semiconductor interfaces are key components in advanced optical devices.

Purpose of the Study:

• To analyze the SHG response of metamaterials with sub-wavelength dielectric-semiconductor interfaces.
• To investigate the role of symmetry breaking in layered metamaterials for enhanced SHG.
• To evaluate amorphous indium gallium zinc oxide (IGZO) as a nonlinear optical material.

Main Methods:

• Fabrication of periodic structures using alternating layers of silicon nitride (50 nm) and IGZO (10 nm) on a quartz substrate.
• Investigation of the SHG response by varying the order of material layers within the elementary cell.
• Characterization of the optical properties and SHG enhancement for structures with an effective thickness of 240 nm.

Main Results:

• The periodic structures exhibited a significantly enhanced SHG response compared to the reference substrate.
• An increase of more than 250-fold in SHG was observed for the fabricated metamaterial structures.
• Amorphous IGZO demonstrated promising nonlinear optical properties, controllable via fabrication processes.

Conclusions:

• The study confirms the potential of engineered dielectric-semiconductor interfaces in metamaterials for boosting SHG.
• Amorphous IGZO is a viable material for nonlinear optics applications.
• Fabrication process control offers a pathway to tune the optical characteristics of these metamaterials for advanced applications.