Enhanced third-harmonic generation in Si-compatible epsilon-near-zero indium tin oxide nanolayers

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Nonlinear optical processes like third-harmonic generation (THG) are crucial for optical signal processing.
• Enhancing nonlinear optical effects in integrated photonic devices is a key challenge.
• Crystalline silicon (Si) offers limited nonlinear efficiency at telecommunication wavelengths.

Purpose of the Study:

• To demonstrate enhanced THG from indium tin oxide (ITO) nanolayers.
• To leverage the epsilon-near-zero (ENZ) property of ITO for increased optical nonlinearity.
• To develop a Si-compatible material platform for integrated nonlinear optics.

Main Methods:

• Fabrication of indium tin oxide nanolayers with tailored ENZ response in the near-infrared.
• Experimental measurement of third-harmonic generation efficiency from ITO nanolayers.
• Comparison of THG efficiency with crystalline silicon (Si).

Main Results:

• Achieved an approximately 600-fold increase in THG efficiency compared to crystalline silicon.
• Demonstrated that the enhanced nonlinearity is due to the ENZ response of the ITO nanolayers.
• Confirmed the compatibility of the ITO nanolayer platform with standard Si-planar technology without specialized nanofabrication.

Conclusions:

• Indium tin oxide nanolayers offer a highly efficient platform for third-harmonic generation.
• The tunable ENZ property of ITO enables significant enhancement of optical nonlinearities.
• This approach facilitates scalable, integrated nonlinear optical functionalities for Si-based devices in information processing and optical sensing.