Tailoring Valley Polarization of Interlayer Excitons in van der Waals Heterostructure toward Optical Communication

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Controlling valley polarization of interlayer excitons is crucial for advancing valleytronic devices.
• Van der Waals heterostructures offer a promising platform for exploring exotic electronic and optical phenomena.

Purpose of the Study:

• To demonstrate the manipulation of valley polarization of interlayer excitons in a WSe2/WS2 heterostructure.
• To investigate the role of a dual-handedness metasurface in enhancing valley polarization.
• To explore potential applications in optical communication and error detection.

Main Methods:

• Fabrication of a monolayer WSe2/WS2 heterostructure integrated with a dual-handedness gold nanoantenna metasurface.
• Optical characterization using circular dichroism (CD) spectroscopy under specific excitation conditions (532 nm, 77 K).
• Analysis of chiral Purcell effects influencing valley polarization.

Main Results:

• The metasurface significantly enhanced the degree of interlayer exciton valley polarization.
• Left-handed metasurface yielded a negative CD of -16%, while the right-handed metasurface yielded a positive CD of +25% under σ+ excitation.
• Tunable CD reached a maximum of 38% at 620 nm under σ- excitation, the highest reported value for interlayer excitons without external fields.

Conclusions:

• Dual-handedness metasurfaces effectively manipulate valley polarization in van der Waals heterostructures.
• The enhanced valley polarization and tunable CD demonstrate potential for advanced valleytronic devices.
• The platform enables direct and byte-invert arithmetic operations, highlighting its utility for error detection in valleytronics-based optical communication.